![Nick Piggin](/assets/img/avatar_default.png)
Lockdep, during self-test (when it was simulating double unlocks) was sometimes unconditionally unlocking a spinlock when it had not been locked. This won't work for ticket locks. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
3232 lines
79 KiB
C
3232 lines
79 KiB
C
/*
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* kernel/lockdep.c
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*
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* Runtime locking correctness validator
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*
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* Started by Ingo Molnar:
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*
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* Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
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*
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* this code maps all the lock dependencies as they occur in a live kernel
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* and will warn about the following classes of locking bugs:
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*
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* - lock inversion scenarios
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* - circular lock dependencies
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* - hardirq/softirq safe/unsafe locking bugs
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*
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* Bugs are reported even if the current locking scenario does not cause
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* any deadlock at this point.
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*
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* I.e. if anytime in the past two locks were taken in a different order,
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* even if it happened for another task, even if those were different
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* locks (but of the same class as this lock), this code will detect it.
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*
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* Thanks to Arjan van de Ven for coming up with the initial idea of
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* mapping lock dependencies runtime.
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*/
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#include <linux/mutex.h>
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#include <linux/sched.h>
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <linux/spinlock.h>
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#include <linux/kallsyms.h>
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#include <linux/interrupt.h>
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#include <linux/stacktrace.h>
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#include <linux/debug_locks.h>
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#include <linux/irqflags.h>
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#include <linux/utsname.h>
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#include <linux/hash.h>
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#include <asm/sections.h>
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#include "lockdep_internals.h"
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#ifdef CONFIG_PROVE_LOCKING
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int prove_locking = 1;
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module_param(prove_locking, int, 0644);
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#else
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#define prove_locking 0
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#endif
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#ifdef CONFIG_LOCK_STAT
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int lock_stat = 1;
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module_param(lock_stat, int, 0644);
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#else
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#define lock_stat 0
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#endif
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/*
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* lockdep_lock: protects the lockdep graph, the hashes and the
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* class/list/hash allocators.
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*
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* This is one of the rare exceptions where it's justified
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* to use a raw spinlock - we really dont want the spinlock
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* code to recurse back into the lockdep code...
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*/
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static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
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static int graph_lock(void)
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{
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__raw_spin_lock(&lockdep_lock);
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/*
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* Make sure that if another CPU detected a bug while
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* walking the graph we dont change it (while the other
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* CPU is busy printing out stuff with the graph lock
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* dropped already)
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*/
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if (!debug_locks) {
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__raw_spin_unlock(&lockdep_lock);
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return 0;
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}
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return 1;
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}
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static inline int graph_unlock(void)
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{
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if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
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return DEBUG_LOCKS_WARN_ON(1);
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__raw_spin_unlock(&lockdep_lock);
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return 0;
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}
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/*
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* Turn lock debugging off and return with 0 if it was off already,
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* and also release the graph lock:
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*/
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static inline int debug_locks_off_graph_unlock(void)
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{
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int ret = debug_locks_off();
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__raw_spin_unlock(&lockdep_lock);
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return ret;
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}
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static int lockdep_initialized;
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unsigned long nr_list_entries;
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static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
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/*
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* All data structures here are protected by the global debug_lock.
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*
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* Mutex key structs only get allocated, once during bootup, and never
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* get freed - this significantly simplifies the debugging code.
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*/
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unsigned long nr_lock_classes;
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static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
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#ifdef CONFIG_LOCK_STAT
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static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
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static int lock_contention_point(struct lock_class *class, unsigned long ip)
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{
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int i;
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for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) {
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if (class->contention_point[i] == 0) {
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class->contention_point[i] = ip;
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break;
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}
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if (class->contention_point[i] == ip)
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break;
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}
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return i;
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}
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static void lock_time_inc(struct lock_time *lt, s64 time)
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{
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if (time > lt->max)
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lt->max = time;
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if (time < lt->min || !lt->min)
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lt->min = time;
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lt->total += time;
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lt->nr++;
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}
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static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
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{
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dst->min += src->min;
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dst->max += src->max;
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dst->total += src->total;
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dst->nr += src->nr;
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}
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struct lock_class_stats lock_stats(struct lock_class *class)
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{
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struct lock_class_stats stats;
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int cpu, i;
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memset(&stats, 0, sizeof(struct lock_class_stats));
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for_each_possible_cpu(cpu) {
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struct lock_class_stats *pcs =
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&per_cpu(lock_stats, cpu)[class - lock_classes];
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for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
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stats.contention_point[i] += pcs->contention_point[i];
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lock_time_add(&pcs->read_waittime, &stats.read_waittime);
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lock_time_add(&pcs->write_waittime, &stats.write_waittime);
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lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
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lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
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for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
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stats.bounces[i] += pcs->bounces[i];
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}
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return stats;
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}
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void clear_lock_stats(struct lock_class *class)
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{
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int cpu;
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for_each_possible_cpu(cpu) {
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struct lock_class_stats *cpu_stats =
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&per_cpu(lock_stats, cpu)[class - lock_classes];
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memset(cpu_stats, 0, sizeof(struct lock_class_stats));
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}
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memset(class->contention_point, 0, sizeof(class->contention_point));
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}
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static struct lock_class_stats *get_lock_stats(struct lock_class *class)
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{
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return &get_cpu_var(lock_stats)[class - lock_classes];
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}
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static void put_lock_stats(struct lock_class_stats *stats)
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{
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put_cpu_var(lock_stats);
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}
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static void lock_release_holdtime(struct held_lock *hlock)
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{
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struct lock_class_stats *stats;
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s64 holdtime;
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if (!lock_stat)
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return;
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holdtime = sched_clock() - hlock->holdtime_stamp;
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stats = get_lock_stats(hlock->class);
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if (hlock->read)
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lock_time_inc(&stats->read_holdtime, holdtime);
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else
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lock_time_inc(&stats->write_holdtime, holdtime);
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put_lock_stats(stats);
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}
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#else
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static inline void lock_release_holdtime(struct held_lock *hlock)
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{
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}
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#endif
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/*
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* We keep a global list of all lock classes. The list only grows,
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* never shrinks. The list is only accessed with the lockdep
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* spinlock lock held.
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*/
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LIST_HEAD(all_lock_classes);
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/*
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* The lockdep classes are in a hash-table as well, for fast lookup:
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*/
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#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
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#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
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#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
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#define classhashentry(key) (classhash_table + __classhashfn((key)))
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static struct list_head classhash_table[CLASSHASH_SIZE];
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/*
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* We put the lock dependency chains into a hash-table as well, to cache
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* their existence:
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*/
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#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
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#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
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#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
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#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
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static struct list_head chainhash_table[CHAINHASH_SIZE];
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/*
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* The hash key of the lock dependency chains is a hash itself too:
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* it's a hash of all locks taken up to that lock, including that lock.
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* It's a 64-bit hash, because it's important for the keys to be
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* unique.
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*/
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#define iterate_chain_key(key1, key2) \
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(((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \
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((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \
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(key2))
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void lockdep_off(void)
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{
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current->lockdep_recursion++;
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}
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EXPORT_SYMBOL(lockdep_off);
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void lockdep_on(void)
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{
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current->lockdep_recursion--;
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}
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EXPORT_SYMBOL(lockdep_on);
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/*
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* Debugging switches:
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*/
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#define VERBOSE 0
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#define VERY_VERBOSE 0
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#if VERBOSE
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# define HARDIRQ_VERBOSE 1
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# define SOFTIRQ_VERBOSE 1
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#else
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# define HARDIRQ_VERBOSE 0
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# define SOFTIRQ_VERBOSE 0
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#endif
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#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
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/*
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* Quick filtering for interesting events:
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*/
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static int class_filter(struct lock_class *class)
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{
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#if 0
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/* Example */
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if (class->name_version == 1 &&
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!strcmp(class->name, "lockname"))
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return 1;
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if (class->name_version == 1 &&
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!strcmp(class->name, "&struct->lockfield"))
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return 1;
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#endif
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/* Filter everything else. 1 would be to allow everything else */
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return 0;
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}
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#endif
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static int verbose(struct lock_class *class)
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{
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#if VERBOSE
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return class_filter(class);
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#endif
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return 0;
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}
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/*
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* Stack-trace: tightly packed array of stack backtrace
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* addresses. Protected by the graph_lock.
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*/
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unsigned long nr_stack_trace_entries;
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static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
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static int save_trace(struct stack_trace *trace)
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{
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trace->nr_entries = 0;
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trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
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trace->entries = stack_trace + nr_stack_trace_entries;
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trace->skip = 3;
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save_stack_trace(trace);
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trace->max_entries = trace->nr_entries;
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nr_stack_trace_entries += trace->nr_entries;
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if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
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if (!debug_locks_off_graph_unlock())
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return 0;
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printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
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printk("turning off the locking correctness validator.\n");
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dump_stack();
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return 0;
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}
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return 1;
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}
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unsigned int nr_hardirq_chains;
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unsigned int nr_softirq_chains;
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unsigned int nr_process_chains;
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unsigned int max_lockdep_depth;
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unsigned int max_recursion_depth;
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#ifdef CONFIG_DEBUG_LOCKDEP
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/*
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* We cannot printk in early bootup code. Not even early_printk()
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* might work. So we mark any initialization errors and printk
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* about it later on, in lockdep_info().
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*/
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static int lockdep_init_error;
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static unsigned long lockdep_init_trace_data[20];
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static struct stack_trace lockdep_init_trace = {
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.max_entries = ARRAY_SIZE(lockdep_init_trace_data),
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.entries = lockdep_init_trace_data,
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};
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/*
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* Various lockdep statistics:
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*/
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atomic_t chain_lookup_hits;
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atomic_t chain_lookup_misses;
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atomic_t hardirqs_on_events;
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atomic_t hardirqs_off_events;
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atomic_t redundant_hardirqs_on;
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atomic_t redundant_hardirqs_off;
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atomic_t softirqs_on_events;
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atomic_t softirqs_off_events;
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atomic_t redundant_softirqs_on;
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atomic_t redundant_softirqs_off;
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atomic_t nr_unused_locks;
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atomic_t nr_cyclic_checks;
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atomic_t nr_cyclic_check_recursions;
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atomic_t nr_find_usage_forwards_checks;
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atomic_t nr_find_usage_forwards_recursions;
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atomic_t nr_find_usage_backwards_checks;
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atomic_t nr_find_usage_backwards_recursions;
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# define debug_atomic_inc(ptr) atomic_inc(ptr)
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# define debug_atomic_dec(ptr) atomic_dec(ptr)
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# define debug_atomic_read(ptr) atomic_read(ptr)
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#else
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# define debug_atomic_inc(ptr) do { } while (0)
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# define debug_atomic_dec(ptr) do { } while (0)
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# define debug_atomic_read(ptr) 0
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#endif
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/*
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* Locking printouts:
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*/
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static const char *usage_str[] =
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{
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[LOCK_USED] = "initial-use ",
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[LOCK_USED_IN_HARDIRQ] = "in-hardirq-W",
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[LOCK_USED_IN_SOFTIRQ] = "in-softirq-W",
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[LOCK_ENABLED_SOFTIRQS] = "softirq-on-W",
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[LOCK_ENABLED_HARDIRQS] = "hardirq-on-W",
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[LOCK_USED_IN_HARDIRQ_READ] = "in-hardirq-R",
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[LOCK_USED_IN_SOFTIRQ_READ] = "in-softirq-R",
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[LOCK_ENABLED_SOFTIRQS_READ] = "softirq-on-R",
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[LOCK_ENABLED_HARDIRQS_READ] = "hardirq-on-R",
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};
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const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
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{
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return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
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}
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void
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get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4)
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{
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*c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.';
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if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
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*c1 = '+';
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else
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if (class->usage_mask & LOCKF_ENABLED_HARDIRQS)
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*c1 = '-';
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if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
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*c2 = '+';
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else
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if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS)
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*c2 = '-';
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if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
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*c3 = '-';
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if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) {
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*c3 = '+';
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if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
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*c3 = '?';
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}
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if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
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*c4 = '-';
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if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) {
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*c4 = '+';
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if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
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*c4 = '?';
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}
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}
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static void print_lock_name(struct lock_class *class)
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{
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char str[KSYM_NAME_LEN], c1, c2, c3, c4;
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const char *name;
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get_usage_chars(class, &c1, &c2, &c3, &c4);
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name = class->name;
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if (!name) {
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name = __get_key_name(class->key, str);
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printk(" (%s", name);
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} else {
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printk(" (%s", name);
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if (class->name_version > 1)
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printk("#%d", class->name_version);
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if (class->subclass)
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printk("/%d", class->subclass);
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}
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printk("){%c%c%c%c}", c1, c2, c3, c4);
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}
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static void print_lockdep_cache(struct lockdep_map *lock)
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{
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const char *name;
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char str[KSYM_NAME_LEN];
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name = lock->name;
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if (!name)
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name = __get_key_name(lock->key->subkeys, str);
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printk("%s", name);
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}
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static void print_lock(struct held_lock *hlock)
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{
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print_lock_name(hlock->class);
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printk(", at: ");
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print_ip_sym(hlock->acquire_ip);
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}
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static void lockdep_print_held_locks(struct task_struct *curr)
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{
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int i, depth = curr->lockdep_depth;
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if (!depth) {
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printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
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return;
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}
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printk("%d lock%s held by %s/%d:\n",
|
|
depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
|
|
|
|
for (i = 0; i < depth; i++) {
|
|
printk(" #%d: ", i);
|
|
print_lock(curr->held_locks + i);
|
|
}
|
|
}
|
|
|
|
static void print_lock_class_header(struct lock_class *class, int depth)
|
|
{
|
|
int bit;
|
|
|
|
printk("%*s->", depth, "");
|
|
print_lock_name(class);
|
|
printk(" ops: %lu", class->ops);
|
|
printk(" {\n");
|
|
|
|
for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
|
|
if (class->usage_mask & (1 << bit)) {
|
|
int len = depth;
|
|
|
|
len += printk("%*s %s", depth, "", usage_str[bit]);
|
|
len += printk(" at:\n");
|
|
print_stack_trace(class->usage_traces + bit, len);
|
|
}
|
|
}
|
|
printk("%*s }\n", depth, "");
|
|
|
|
printk("%*s ... key at: ",depth,"");
|
|
print_ip_sym((unsigned long)class->key);
|
|
}
|
|
|
|
/*
|
|
* printk all lock dependencies starting at <entry>:
|
|
*/
|
|
static void print_lock_dependencies(struct lock_class *class, int depth)
|
|
{
|
|
struct lock_list *entry;
|
|
|
|
if (DEBUG_LOCKS_WARN_ON(depth >= 20))
|
|
return;
|
|
|
|
print_lock_class_header(class, depth);
|
|
|
|
list_for_each_entry(entry, &class->locks_after, entry) {
|
|
if (DEBUG_LOCKS_WARN_ON(!entry->class))
|
|
return;
|
|
|
|
print_lock_dependencies(entry->class, depth + 1);
|
|
|
|
printk("%*s ... acquired at:\n",depth,"");
|
|
print_stack_trace(&entry->trace, 2);
|
|
printk("\n");
|
|
}
|
|
}
|
|
|
|
static void print_kernel_version(void)
|
|
{
|
|
printk("%s %.*s\n", init_utsname()->release,
|
|
(int)strcspn(init_utsname()->version, " "),
|
|
init_utsname()->version);
|
|
}
|
|
|
|
static int very_verbose(struct lock_class *class)
|
|
{
|
|
#if VERY_VERBOSE
|
|
return class_filter(class);
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Is this the address of a static object:
|
|
*/
|
|
static int static_obj(void *obj)
|
|
{
|
|
unsigned long start = (unsigned long) &_stext,
|
|
end = (unsigned long) &_end,
|
|
addr = (unsigned long) obj;
|
|
#ifdef CONFIG_SMP
|
|
int i;
|
|
#endif
|
|
|
|
/*
|
|
* static variable?
|
|
*/
|
|
if ((addr >= start) && (addr < end))
|
|
return 1;
|
|
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* percpu var?
|
|
*/
|
|
for_each_possible_cpu(i) {
|
|
start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
|
|
end = (unsigned long) &__per_cpu_start + PERCPU_ENOUGH_ROOM
|
|
+ per_cpu_offset(i);
|
|
|
|
if ((addr >= start) && (addr < end))
|
|
return 1;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* module var?
|
|
*/
|
|
return is_module_address(addr);
|
|
}
|
|
|
|
/*
|
|
* To make lock name printouts unique, we calculate a unique
|
|
* class->name_version generation counter:
|
|
*/
|
|
static int count_matching_names(struct lock_class *new_class)
|
|
{
|
|
struct lock_class *class;
|
|
int count = 0;
|
|
|
|
if (!new_class->name)
|
|
return 0;
|
|
|
|
list_for_each_entry(class, &all_lock_classes, lock_entry) {
|
|
if (new_class->key - new_class->subclass == class->key)
|
|
return class->name_version;
|
|
if (class->name && !strcmp(class->name, new_class->name))
|
|
count = max(count, class->name_version);
|
|
}
|
|
|
|
return count + 1;
|
|
}
|
|
|
|
/*
|
|
* Register a lock's class in the hash-table, if the class is not present
|
|
* yet. Otherwise we look it up. We cache the result in the lock object
|
|
* itself, so actual lookup of the hash should be once per lock object.
|
|
*/
|
|
static inline struct lock_class *
|
|
look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
|
|
{
|
|
struct lockdep_subclass_key *key;
|
|
struct list_head *hash_head;
|
|
struct lock_class *class;
|
|
|
|
#ifdef CONFIG_DEBUG_LOCKDEP
|
|
/*
|
|
* If the architecture calls into lockdep before initializing
|
|
* the hashes then we'll warn about it later. (we cannot printk
|
|
* right now)
|
|
*/
|
|
if (unlikely(!lockdep_initialized)) {
|
|
lockdep_init();
|
|
lockdep_init_error = 1;
|
|
save_stack_trace(&lockdep_init_trace);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Static locks do not have their class-keys yet - for them the key
|
|
* is the lock object itself:
|
|
*/
|
|
if (unlikely(!lock->key))
|
|
lock->key = (void *)lock;
|
|
|
|
/*
|
|
* NOTE: the class-key must be unique. For dynamic locks, a static
|
|
* lock_class_key variable is passed in through the mutex_init()
|
|
* (or spin_lock_init()) call - which acts as the key. For static
|
|
* locks we use the lock object itself as the key.
|
|
*/
|
|
BUILD_BUG_ON(sizeof(struct lock_class_key) >
|
|
sizeof(struct lockdep_map));
|
|
|
|
key = lock->key->subkeys + subclass;
|
|
|
|
hash_head = classhashentry(key);
|
|
|
|
/*
|
|
* We can walk the hash lockfree, because the hash only
|
|
* grows, and we are careful when adding entries to the end:
|
|
*/
|
|
list_for_each_entry(class, hash_head, hash_entry) {
|
|
if (class->key == key) {
|
|
WARN_ON_ONCE(class->name != lock->name);
|
|
return class;
|
|
}
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Register a lock's class in the hash-table, if the class is not present
|
|
* yet. Otherwise we look it up. We cache the result in the lock object
|
|
* itself, so actual lookup of the hash should be once per lock object.
|
|
*/
|
|
static inline struct lock_class *
|
|
register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
|
|
{
|
|
struct lockdep_subclass_key *key;
|
|
struct list_head *hash_head;
|
|
struct lock_class *class;
|
|
unsigned long flags;
|
|
|
|
class = look_up_lock_class(lock, subclass);
|
|
if (likely(class))
|
|
return class;
|
|
|
|
/*
|
|
* Debug-check: all keys must be persistent!
|
|
*/
|
|
if (!static_obj(lock->key)) {
|
|
debug_locks_off();
|
|
printk("INFO: trying to register non-static key.\n");
|
|
printk("the code is fine but needs lockdep annotation.\n");
|
|
printk("turning off the locking correctness validator.\n");
|
|
dump_stack();
|
|
|
|
return NULL;
|
|
}
|
|
|
|
key = lock->key->subkeys + subclass;
|
|
hash_head = classhashentry(key);
|
|
|
|
raw_local_irq_save(flags);
|
|
if (!graph_lock()) {
|
|
raw_local_irq_restore(flags);
|
|
return NULL;
|
|
}
|
|
/*
|
|
* We have to do the hash-walk again, to avoid races
|
|
* with another CPU:
|
|
*/
|
|
list_for_each_entry(class, hash_head, hash_entry)
|
|
if (class->key == key)
|
|
goto out_unlock_set;
|
|
/*
|
|
* Allocate a new key from the static array, and add it to
|
|
* the hash:
|
|
*/
|
|
if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
|
|
if (!debug_locks_off_graph_unlock()) {
|
|
raw_local_irq_restore(flags);
|
|
return NULL;
|
|
}
|
|
raw_local_irq_restore(flags);
|
|
|
|
printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
|
|
printk("turning off the locking correctness validator.\n");
|
|
return NULL;
|
|
}
|
|
class = lock_classes + nr_lock_classes++;
|
|
debug_atomic_inc(&nr_unused_locks);
|
|
class->key = key;
|
|
class->name = lock->name;
|
|
class->subclass = subclass;
|
|
INIT_LIST_HEAD(&class->lock_entry);
|
|
INIT_LIST_HEAD(&class->locks_before);
|
|
INIT_LIST_HEAD(&class->locks_after);
|
|
class->name_version = count_matching_names(class);
|
|
/*
|
|
* We use RCU's safe list-add method to make
|
|
* parallel walking of the hash-list safe:
|
|
*/
|
|
list_add_tail_rcu(&class->hash_entry, hash_head);
|
|
|
|
if (verbose(class)) {
|
|
graph_unlock();
|
|
raw_local_irq_restore(flags);
|
|
|
|
printk("\nnew class %p: %s", class->key, class->name);
|
|
if (class->name_version > 1)
|
|
printk("#%d", class->name_version);
|
|
printk("\n");
|
|
dump_stack();
|
|
|
|
raw_local_irq_save(flags);
|
|
if (!graph_lock()) {
|
|
raw_local_irq_restore(flags);
|
|
return NULL;
|
|
}
|
|
}
|
|
out_unlock_set:
|
|
graph_unlock();
|
|
raw_local_irq_restore(flags);
|
|
|
|
if (!subclass || force)
|
|
lock->class_cache = class;
|
|
|
|
if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
|
|
return NULL;
|
|
|
|
return class;
|
|
}
|
|
|
|
#ifdef CONFIG_PROVE_LOCKING
|
|
/*
|
|
* Allocate a lockdep entry. (assumes the graph_lock held, returns
|
|
* with NULL on failure)
|
|
*/
|
|
static struct lock_list *alloc_list_entry(void)
|
|
{
|
|
if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
|
|
if (!debug_locks_off_graph_unlock())
|
|
return NULL;
|
|
|
|
printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
|
|
printk("turning off the locking correctness validator.\n");
|
|
return NULL;
|
|
}
|
|
return list_entries + nr_list_entries++;
|
|
}
|
|
|
|
/*
|
|
* Add a new dependency to the head of the list:
|
|
*/
|
|
static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
|
|
struct list_head *head, unsigned long ip, int distance)
|
|
{
|
|
struct lock_list *entry;
|
|
/*
|
|
* Lock not present yet - get a new dependency struct and
|
|
* add it to the list:
|
|
*/
|
|
entry = alloc_list_entry();
|
|
if (!entry)
|
|
return 0;
|
|
|
|
entry->class = this;
|
|
entry->distance = distance;
|
|
if (!save_trace(&entry->trace))
|
|
return 0;
|
|
|
|
/*
|
|
* Since we never remove from the dependency list, the list can
|
|
* be walked lockless by other CPUs, it's only allocation
|
|
* that must be protected by the spinlock. But this also means
|
|
* we must make new entries visible only once writes to the
|
|
* entry become visible - hence the RCU op:
|
|
*/
|
|
list_add_tail_rcu(&entry->entry, head);
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Recursive, forwards-direction lock-dependency checking, used for
|
|
* both noncyclic checking and for hardirq-unsafe/softirq-unsafe
|
|
* checking.
|
|
*
|
|
* (to keep the stackframe of the recursive functions small we
|
|
* use these global variables, and we also mark various helper
|
|
* functions as noinline.)
|
|
*/
|
|
static struct held_lock *check_source, *check_target;
|
|
|
|
/*
|
|
* Print a dependency chain entry (this is only done when a deadlock
|
|
* has been detected):
|
|
*/
|
|
static noinline int
|
|
print_circular_bug_entry(struct lock_list *target, unsigned int depth)
|
|
{
|
|
if (debug_locks_silent)
|
|
return 0;
|
|
printk("\n-> #%u", depth);
|
|
print_lock_name(target->class);
|
|
printk(":\n");
|
|
print_stack_trace(&target->trace, 6);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* When a circular dependency is detected, print the
|
|
* header first:
|
|
*/
|
|
static noinline int
|
|
print_circular_bug_header(struct lock_list *entry, unsigned int depth)
|
|
{
|
|
struct task_struct *curr = current;
|
|
|
|
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
|
|
return 0;
|
|
|
|
printk("\n=======================================================\n");
|
|
printk( "[ INFO: possible circular locking dependency detected ]\n");
|
|
print_kernel_version();
|
|
printk( "-------------------------------------------------------\n");
|
|
printk("%s/%d is trying to acquire lock:\n",
|
|
curr->comm, task_pid_nr(curr));
|
|
print_lock(check_source);
|
|
printk("\nbut task is already holding lock:\n");
|
|
print_lock(check_target);
|
|
printk("\nwhich lock already depends on the new lock.\n\n");
|
|
printk("\nthe existing dependency chain (in reverse order) is:\n");
|
|
|
|
print_circular_bug_entry(entry, depth);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static noinline int print_circular_bug_tail(void)
|
|
{
|
|
struct task_struct *curr = current;
|
|
struct lock_list this;
|
|
|
|
if (debug_locks_silent)
|
|
return 0;
|
|
|
|
this.class = check_source->class;
|
|
if (!save_trace(&this.trace))
|
|
return 0;
|
|
|
|
print_circular_bug_entry(&this, 0);
|
|
|
|
printk("\nother info that might help us debug this:\n\n");
|
|
lockdep_print_held_locks(curr);
|
|
|
|
printk("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
#define RECURSION_LIMIT 40
|
|
|
|
static int noinline print_infinite_recursion_bug(void)
|
|
{
|
|
if (!debug_locks_off_graph_unlock())
|
|
return 0;
|
|
|
|
WARN_ON(1);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Prove that the dependency graph starting at <entry> can not
|
|
* lead to <target>. Print an error and return 0 if it does.
|
|
*/
|
|
static noinline int
|
|
check_noncircular(struct lock_class *source, unsigned int depth)
|
|
{
|
|
struct lock_list *entry;
|
|
|
|
debug_atomic_inc(&nr_cyclic_check_recursions);
|
|
if (depth > max_recursion_depth)
|
|
max_recursion_depth = depth;
|
|
if (depth >= RECURSION_LIMIT)
|
|
return print_infinite_recursion_bug();
|
|
/*
|
|
* Check this lock's dependency list:
|
|
*/
|
|
list_for_each_entry(entry, &source->locks_after, entry) {
|
|
if (entry->class == check_target->class)
|
|
return print_circular_bug_header(entry, depth+1);
|
|
debug_atomic_inc(&nr_cyclic_checks);
|
|
if (!check_noncircular(entry->class, depth+1))
|
|
return print_circular_bug_entry(entry, depth+1);
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
#ifdef CONFIG_TRACE_IRQFLAGS
|
|
/*
|
|
* Forwards and backwards subgraph searching, for the purposes of
|
|
* proving that two subgraphs can be connected by a new dependency
|
|
* without creating any illegal irq-safe -> irq-unsafe lock dependency.
|
|
*/
|
|
static enum lock_usage_bit find_usage_bit;
|
|
static struct lock_class *forwards_match, *backwards_match;
|
|
|
|
/*
|
|
* Find a node in the forwards-direction dependency sub-graph starting
|
|
* at <source> that matches <find_usage_bit>.
|
|
*
|
|
* Return 2 if such a node exists in the subgraph, and put that node
|
|
* into <forwards_match>.
|
|
*
|
|
* Return 1 otherwise and keep <forwards_match> unchanged.
|
|
* Return 0 on error.
|
|
*/
|
|
static noinline int
|
|
find_usage_forwards(struct lock_class *source, unsigned int depth)
|
|
{
|
|
struct lock_list *entry;
|
|
int ret;
|
|
|
|
if (depth > max_recursion_depth)
|
|
max_recursion_depth = depth;
|
|
if (depth >= RECURSION_LIMIT)
|
|
return print_infinite_recursion_bug();
|
|
|
|
debug_atomic_inc(&nr_find_usage_forwards_checks);
|
|
if (source->usage_mask & (1 << find_usage_bit)) {
|
|
forwards_match = source;
|
|
return 2;
|
|
}
|
|
|
|
/*
|
|
* Check this lock's dependency list:
|
|
*/
|
|
list_for_each_entry(entry, &source->locks_after, entry) {
|
|
debug_atomic_inc(&nr_find_usage_forwards_recursions);
|
|
ret = find_usage_forwards(entry->class, depth+1);
|
|
if (ret == 2 || ret == 0)
|
|
return ret;
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Find a node in the backwards-direction dependency sub-graph starting
|
|
* at <source> that matches <find_usage_bit>.
|
|
*
|
|
* Return 2 if such a node exists in the subgraph, and put that node
|
|
* into <backwards_match>.
|
|
*
|
|
* Return 1 otherwise and keep <backwards_match> unchanged.
|
|
* Return 0 on error.
|
|
*/
|
|
static noinline int
|
|
find_usage_backwards(struct lock_class *source, unsigned int depth)
|
|
{
|
|
struct lock_list *entry;
|
|
int ret;
|
|
|
|
if (!__raw_spin_is_locked(&lockdep_lock))
|
|
return DEBUG_LOCKS_WARN_ON(1);
|
|
|
|
if (depth > max_recursion_depth)
|
|
max_recursion_depth = depth;
|
|
if (depth >= RECURSION_LIMIT)
|
|
return print_infinite_recursion_bug();
|
|
|
|
debug_atomic_inc(&nr_find_usage_backwards_checks);
|
|
if (source->usage_mask & (1 << find_usage_bit)) {
|
|
backwards_match = source;
|
|
return 2;
|
|
}
|
|
|
|
/*
|
|
* Check this lock's dependency list:
|
|
*/
|
|
list_for_each_entry(entry, &source->locks_before, entry) {
|
|
debug_atomic_inc(&nr_find_usage_backwards_recursions);
|
|
ret = find_usage_backwards(entry->class, depth+1);
|
|
if (ret == 2 || ret == 0)
|
|
return ret;
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
static int
|
|
print_bad_irq_dependency(struct task_struct *curr,
|
|
struct held_lock *prev,
|
|
struct held_lock *next,
|
|
enum lock_usage_bit bit1,
|
|
enum lock_usage_bit bit2,
|
|
const char *irqclass)
|
|
{
|
|
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
|
|
return 0;
|
|
|
|
printk("\n======================================================\n");
|
|
printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
|
|
irqclass, irqclass);
|
|
print_kernel_version();
|
|
printk( "------------------------------------------------------\n");
|
|
printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
|
|
curr->comm, task_pid_nr(curr),
|
|
curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
|
|
curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
|
|
curr->hardirqs_enabled,
|
|
curr->softirqs_enabled);
|
|
print_lock(next);
|
|
|
|
printk("\nand this task is already holding:\n");
|
|
print_lock(prev);
|
|
printk("which would create a new lock dependency:\n");
|
|
print_lock_name(prev->class);
|
|
printk(" ->");
|
|
print_lock_name(next->class);
|
|
printk("\n");
|
|
|
|
printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
|
|
irqclass);
|
|
print_lock_name(backwards_match);
|
|
printk("\n... which became %s-irq-safe at:\n", irqclass);
|
|
|
|
print_stack_trace(backwards_match->usage_traces + bit1, 1);
|
|
|
|
printk("\nto a %s-irq-unsafe lock:\n", irqclass);
|
|
print_lock_name(forwards_match);
|
|
printk("\n... which became %s-irq-unsafe at:\n", irqclass);
|
|
printk("...");
|
|
|
|
print_stack_trace(forwards_match->usage_traces + bit2, 1);
|
|
|
|
printk("\nother info that might help us debug this:\n\n");
|
|
lockdep_print_held_locks(curr);
|
|
|
|
printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
|
|
print_lock_dependencies(backwards_match, 0);
|
|
|
|
printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
|
|
print_lock_dependencies(forwards_match, 0);
|
|
|
|
printk("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
check_usage(struct task_struct *curr, struct held_lock *prev,
|
|
struct held_lock *next, enum lock_usage_bit bit_backwards,
|
|
enum lock_usage_bit bit_forwards, const char *irqclass)
|
|
{
|
|
int ret;
|
|
|
|
find_usage_bit = bit_backwards;
|
|
/* fills in <backwards_match> */
|
|
ret = find_usage_backwards(prev->class, 0);
|
|
if (!ret || ret == 1)
|
|
return ret;
|
|
|
|
find_usage_bit = bit_forwards;
|
|
ret = find_usage_forwards(next->class, 0);
|
|
if (!ret || ret == 1)
|
|
return ret;
|
|
/* ret == 2 */
|
|
return print_bad_irq_dependency(curr, prev, next,
|
|
bit_backwards, bit_forwards, irqclass);
|
|
}
|
|
|
|
static int
|
|
check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
|
|
struct held_lock *next)
|
|
{
|
|
/*
|
|
* Prove that the new dependency does not connect a hardirq-safe
|
|
* lock with a hardirq-unsafe lock - to achieve this we search
|
|
* the backwards-subgraph starting at <prev>, and the
|
|
* forwards-subgraph starting at <next>:
|
|
*/
|
|
if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
|
|
LOCK_ENABLED_HARDIRQS, "hard"))
|
|
return 0;
|
|
|
|
/*
|
|
* Prove that the new dependency does not connect a hardirq-safe-read
|
|
* lock with a hardirq-unsafe lock - to achieve this we search
|
|
* the backwards-subgraph starting at <prev>, and the
|
|
* forwards-subgraph starting at <next>:
|
|
*/
|
|
if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
|
|
LOCK_ENABLED_HARDIRQS, "hard-read"))
|
|
return 0;
|
|
|
|
/*
|
|
* Prove that the new dependency does not connect a softirq-safe
|
|
* lock with a softirq-unsafe lock - to achieve this we search
|
|
* the backwards-subgraph starting at <prev>, and the
|
|
* forwards-subgraph starting at <next>:
|
|
*/
|
|
if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
|
|
LOCK_ENABLED_SOFTIRQS, "soft"))
|
|
return 0;
|
|
/*
|
|
* Prove that the new dependency does not connect a softirq-safe-read
|
|
* lock with a softirq-unsafe lock - to achieve this we search
|
|
* the backwards-subgraph starting at <prev>, and the
|
|
* forwards-subgraph starting at <next>:
|
|
*/
|
|
if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
|
|
LOCK_ENABLED_SOFTIRQS, "soft"))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static void inc_chains(void)
|
|
{
|
|
if (current->hardirq_context)
|
|
nr_hardirq_chains++;
|
|
else {
|
|
if (current->softirq_context)
|
|
nr_softirq_chains++;
|
|
else
|
|
nr_process_chains++;
|
|
}
|
|
}
|
|
|
|
#else
|
|
|
|
static inline int
|
|
check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
|
|
struct held_lock *next)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
static inline void inc_chains(void)
|
|
{
|
|
nr_process_chains++;
|
|
}
|
|
|
|
#endif
|
|
|
|
static int
|
|
print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
|
|
struct held_lock *next)
|
|
{
|
|
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
|
|
return 0;
|
|
|
|
printk("\n=============================================\n");
|
|
printk( "[ INFO: possible recursive locking detected ]\n");
|
|
print_kernel_version();
|
|
printk( "---------------------------------------------\n");
|
|
printk("%s/%d is trying to acquire lock:\n",
|
|
curr->comm, task_pid_nr(curr));
|
|
print_lock(next);
|
|
printk("\nbut task is already holding lock:\n");
|
|
print_lock(prev);
|
|
|
|
printk("\nother info that might help us debug this:\n");
|
|
lockdep_print_held_locks(curr);
|
|
|
|
printk("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Check whether we are holding such a class already.
|
|
*
|
|
* (Note that this has to be done separately, because the graph cannot
|
|
* detect such classes of deadlocks.)
|
|
*
|
|
* Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
|
|
*/
|
|
static int
|
|
check_deadlock(struct task_struct *curr, struct held_lock *next,
|
|
struct lockdep_map *next_instance, int read)
|
|
{
|
|
struct held_lock *prev;
|
|
int i;
|
|
|
|
for (i = 0; i < curr->lockdep_depth; i++) {
|
|
prev = curr->held_locks + i;
|
|
if (prev->class != next->class)
|
|
continue;
|
|
/*
|
|
* Allow read-after-read recursion of the same
|
|
* lock class (i.e. read_lock(lock)+read_lock(lock)):
|
|
*/
|
|
if ((read == 2) && prev->read)
|
|
return 2;
|
|
return print_deadlock_bug(curr, prev, next);
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* There was a chain-cache miss, and we are about to add a new dependency
|
|
* to a previous lock. We recursively validate the following rules:
|
|
*
|
|
* - would the adding of the <prev> -> <next> dependency create a
|
|
* circular dependency in the graph? [== circular deadlock]
|
|
*
|
|
* - does the new prev->next dependency connect any hardirq-safe lock
|
|
* (in the full backwards-subgraph starting at <prev>) with any
|
|
* hardirq-unsafe lock (in the full forwards-subgraph starting at
|
|
* <next>)? [== illegal lock inversion with hardirq contexts]
|
|
*
|
|
* - does the new prev->next dependency connect any softirq-safe lock
|
|
* (in the full backwards-subgraph starting at <prev>) with any
|
|
* softirq-unsafe lock (in the full forwards-subgraph starting at
|
|
* <next>)? [== illegal lock inversion with softirq contexts]
|
|
*
|
|
* any of these scenarios could lead to a deadlock.
|
|
*
|
|
* Then if all the validations pass, we add the forwards and backwards
|
|
* dependency.
|
|
*/
|
|
static int
|
|
check_prev_add(struct task_struct *curr, struct held_lock *prev,
|
|
struct held_lock *next, int distance)
|
|
{
|
|
struct lock_list *entry;
|
|
int ret;
|
|
|
|
/*
|
|
* Prove that the new <prev> -> <next> dependency would not
|
|
* create a circular dependency in the graph. (We do this by
|
|
* forward-recursing into the graph starting at <next>, and
|
|
* checking whether we can reach <prev>.)
|
|
*
|
|
* We are using global variables to control the recursion, to
|
|
* keep the stackframe size of the recursive functions low:
|
|
*/
|
|
check_source = next;
|
|
check_target = prev;
|
|
if (!(check_noncircular(next->class, 0)))
|
|
return print_circular_bug_tail();
|
|
|
|
if (!check_prev_add_irq(curr, prev, next))
|
|
return 0;
|
|
|
|
/*
|
|
* For recursive read-locks we do all the dependency checks,
|
|
* but we dont store read-triggered dependencies (only
|
|
* write-triggered dependencies). This ensures that only the
|
|
* write-side dependencies matter, and that if for example a
|
|
* write-lock never takes any other locks, then the reads are
|
|
* equivalent to a NOP.
|
|
*/
|
|
if (next->read == 2 || prev->read == 2)
|
|
return 1;
|
|
/*
|
|
* Is the <prev> -> <next> dependency already present?
|
|
*
|
|
* (this may occur even though this is a new chain: consider
|
|
* e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
|
|
* chains - the second one will be new, but L1 already has
|
|
* L2 added to its dependency list, due to the first chain.)
|
|
*/
|
|
list_for_each_entry(entry, &prev->class->locks_after, entry) {
|
|
if (entry->class == next->class) {
|
|
if (distance == 1)
|
|
entry->distance = 1;
|
|
return 2;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Ok, all validations passed, add the new lock
|
|
* to the previous lock's dependency list:
|
|
*/
|
|
ret = add_lock_to_list(prev->class, next->class,
|
|
&prev->class->locks_after, next->acquire_ip, distance);
|
|
|
|
if (!ret)
|
|
return 0;
|
|
|
|
ret = add_lock_to_list(next->class, prev->class,
|
|
&next->class->locks_before, next->acquire_ip, distance);
|
|
if (!ret)
|
|
return 0;
|
|
|
|
/*
|
|
* Debugging printouts:
|
|
*/
|
|
if (verbose(prev->class) || verbose(next->class)) {
|
|
graph_unlock();
|
|
printk("\n new dependency: ");
|
|
print_lock_name(prev->class);
|
|
printk(" => ");
|
|
print_lock_name(next->class);
|
|
printk("\n");
|
|
dump_stack();
|
|
return graph_lock();
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Add the dependency to all directly-previous locks that are 'relevant'.
|
|
* The ones that are relevant are (in increasing distance from curr):
|
|
* all consecutive trylock entries and the final non-trylock entry - or
|
|
* the end of this context's lock-chain - whichever comes first.
|
|
*/
|
|
static int
|
|
check_prevs_add(struct task_struct *curr, struct held_lock *next)
|
|
{
|
|
int depth = curr->lockdep_depth;
|
|
struct held_lock *hlock;
|
|
|
|
/*
|
|
* Debugging checks.
|
|
*
|
|
* Depth must not be zero for a non-head lock:
|
|
*/
|
|
if (!depth)
|
|
goto out_bug;
|
|
/*
|
|
* At least two relevant locks must exist for this
|
|
* to be a head:
|
|
*/
|
|
if (curr->held_locks[depth].irq_context !=
|
|
curr->held_locks[depth-1].irq_context)
|
|
goto out_bug;
|
|
|
|
for (;;) {
|
|
int distance = curr->lockdep_depth - depth + 1;
|
|
hlock = curr->held_locks + depth-1;
|
|
/*
|
|
* Only non-recursive-read entries get new dependencies
|
|
* added:
|
|
*/
|
|
if (hlock->read != 2) {
|
|
if (!check_prev_add(curr, hlock, next, distance))
|
|
return 0;
|
|
/*
|
|
* Stop after the first non-trylock entry,
|
|
* as non-trylock entries have added their
|
|
* own direct dependencies already, so this
|
|
* lock is connected to them indirectly:
|
|
*/
|
|
if (!hlock->trylock)
|
|
break;
|
|
}
|
|
depth--;
|
|
/*
|
|
* End of lock-stack?
|
|
*/
|
|
if (!depth)
|
|
break;
|
|
/*
|
|
* Stop the search if we cross into another context:
|
|
*/
|
|
if (curr->held_locks[depth].irq_context !=
|
|
curr->held_locks[depth-1].irq_context)
|
|
break;
|
|
}
|
|
return 1;
|
|
out_bug:
|
|
if (!debug_locks_off_graph_unlock())
|
|
return 0;
|
|
|
|
WARN_ON(1);
|
|
|
|
return 0;
|
|
}
|
|
|
|
unsigned long nr_lock_chains;
|
|
static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
|
|
|
|
/*
|
|
* Look up a dependency chain. If the key is not present yet then
|
|
* add it and return 1 - in this case the new dependency chain is
|
|
* validated. If the key is already hashed, return 0.
|
|
* (On return with 1 graph_lock is held.)
|
|
*/
|
|
static inline int lookup_chain_cache(u64 chain_key, struct lock_class *class)
|
|
{
|
|
struct list_head *hash_head = chainhashentry(chain_key);
|
|
struct lock_chain *chain;
|
|
|
|
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
|
|
return 0;
|
|
/*
|
|
* We can walk it lock-free, because entries only get added
|
|
* to the hash:
|
|
*/
|
|
list_for_each_entry(chain, hash_head, entry) {
|
|
if (chain->chain_key == chain_key) {
|
|
cache_hit:
|
|
debug_atomic_inc(&chain_lookup_hits);
|
|
if (very_verbose(class))
|
|
printk("\nhash chain already cached, key: "
|
|
"%016Lx tail class: [%p] %s\n",
|
|
(unsigned long long)chain_key,
|
|
class->key, class->name);
|
|
return 0;
|
|
}
|
|
}
|
|
if (very_verbose(class))
|
|
printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
|
|
(unsigned long long)chain_key, class->key, class->name);
|
|
/*
|
|
* Allocate a new chain entry from the static array, and add
|
|
* it to the hash:
|
|
*/
|
|
if (!graph_lock())
|
|
return 0;
|
|
/*
|
|
* We have to walk the chain again locked - to avoid duplicates:
|
|
*/
|
|
list_for_each_entry(chain, hash_head, entry) {
|
|
if (chain->chain_key == chain_key) {
|
|
graph_unlock();
|
|
goto cache_hit;
|
|
}
|
|
}
|
|
if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
|
|
if (!debug_locks_off_graph_unlock())
|
|
return 0;
|
|
|
|
printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
|
|
printk("turning off the locking correctness validator.\n");
|
|
return 0;
|
|
}
|
|
chain = lock_chains + nr_lock_chains++;
|
|
chain->chain_key = chain_key;
|
|
list_add_tail_rcu(&chain->entry, hash_head);
|
|
debug_atomic_inc(&chain_lookup_misses);
|
|
inc_chains();
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
|
|
struct held_lock *hlock, int chain_head, u64 chain_key)
|
|
{
|
|
/*
|
|
* Trylock needs to maintain the stack of held locks, but it
|
|
* does not add new dependencies, because trylock can be done
|
|
* in any order.
|
|
*
|
|
* We look up the chain_key and do the O(N^2) check and update of
|
|
* the dependencies only if this is a new dependency chain.
|
|
* (If lookup_chain_cache() returns with 1 it acquires
|
|
* graph_lock for us)
|
|
*/
|
|
if (!hlock->trylock && (hlock->check == 2) &&
|
|
lookup_chain_cache(chain_key, hlock->class)) {
|
|
/*
|
|
* Check whether last held lock:
|
|
*
|
|
* - is irq-safe, if this lock is irq-unsafe
|
|
* - is softirq-safe, if this lock is hardirq-unsafe
|
|
*
|
|
* And check whether the new lock's dependency graph
|
|
* could lead back to the previous lock.
|
|
*
|
|
* any of these scenarios could lead to a deadlock. If
|
|
* All validations
|
|
*/
|
|
int ret = check_deadlock(curr, hlock, lock, hlock->read);
|
|
|
|
if (!ret)
|
|
return 0;
|
|
/*
|
|
* Mark recursive read, as we jump over it when
|
|
* building dependencies (just like we jump over
|
|
* trylock entries):
|
|
*/
|
|
if (ret == 2)
|
|
hlock->read = 2;
|
|
/*
|
|
* Add dependency only if this lock is not the head
|
|
* of the chain, and if it's not a secondary read-lock:
|
|
*/
|
|
if (!chain_head && ret != 2)
|
|
if (!check_prevs_add(curr, hlock))
|
|
return 0;
|
|
graph_unlock();
|
|
} else
|
|
/* after lookup_chain_cache(): */
|
|
if (unlikely(!debug_locks))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
#else
|
|
static inline int validate_chain(struct task_struct *curr,
|
|
struct lockdep_map *lock, struct held_lock *hlock,
|
|
int chain_head, u64 chain_key)
|
|
{
|
|
return 1;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* We are building curr_chain_key incrementally, so double-check
|
|
* it from scratch, to make sure that it's done correctly:
|
|
*/
|
|
static void check_chain_key(struct task_struct *curr)
|
|
{
|
|
#ifdef CONFIG_DEBUG_LOCKDEP
|
|
struct held_lock *hlock, *prev_hlock = NULL;
|
|
unsigned int i, id;
|
|
u64 chain_key = 0;
|
|
|
|
for (i = 0; i < curr->lockdep_depth; i++) {
|
|
hlock = curr->held_locks + i;
|
|
if (chain_key != hlock->prev_chain_key) {
|
|
debug_locks_off();
|
|
printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
|
|
curr->lockdep_depth, i,
|
|
(unsigned long long)chain_key,
|
|
(unsigned long long)hlock->prev_chain_key);
|
|
WARN_ON(1);
|
|
return;
|
|
}
|
|
id = hlock->class - lock_classes;
|
|
if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
|
|
return;
|
|
|
|
if (prev_hlock && (prev_hlock->irq_context !=
|
|
hlock->irq_context))
|
|
chain_key = 0;
|
|
chain_key = iterate_chain_key(chain_key, id);
|
|
prev_hlock = hlock;
|
|
}
|
|
if (chain_key != curr->curr_chain_key) {
|
|
debug_locks_off();
|
|
printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
|
|
curr->lockdep_depth, i,
|
|
(unsigned long long)chain_key,
|
|
(unsigned long long)curr->curr_chain_key);
|
|
WARN_ON(1);
|
|
}
|
|
#endif
|
|
}
|
|
|
|
static int
|
|
print_usage_bug(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
|
|
{
|
|
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
|
|
return 0;
|
|
|
|
printk("\n=================================\n");
|
|
printk( "[ INFO: inconsistent lock state ]\n");
|
|
print_kernel_version();
|
|
printk( "---------------------------------\n");
|
|
|
|
printk("inconsistent {%s} -> {%s} usage.\n",
|
|
usage_str[prev_bit], usage_str[new_bit]);
|
|
|
|
printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
|
|
curr->comm, task_pid_nr(curr),
|
|
trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
|
|
trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
|
|
trace_hardirqs_enabled(curr),
|
|
trace_softirqs_enabled(curr));
|
|
print_lock(this);
|
|
|
|
printk("{%s} state was registered at:\n", usage_str[prev_bit]);
|
|
print_stack_trace(this->class->usage_traces + prev_bit, 1);
|
|
|
|
print_irqtrace_events(curr);
|
|
printk("\nother info that might help us debug this:\n");
|
|
lockdep_print_held_locks(curr);
|
|
|
|
printk("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Print out an error if an invalid bit is set:
|
|
*/
|
|
static inline int
|
|
valid_state(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
|
|
{
|
|
if (unlikely(this->class->usage_mask & (1 << bad_bit)))
|
|
return print_usage_bug(curr, this, bad_bit, new_bit);
|
|
return 1;
|
|
}
|
|
|
|
static int mark_lock(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit new_bit);
|
|
|
|
#ifdef CONFIG_TRACE_IRQFLAGS
|
|
|
|
/*
|
|
* print irq inversion bug:
|
|
*/
|
|
static int
|
|
print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
|
|
struct held_lock *this, int forwards,
|
|
const char *irqclass)
|
|
{
|
|
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
|
|
return 0;
|
|
|
|
printk("\n=========================================================\n");
|
|
printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
|
|
print_kernel_version();
|
|
printk( "---------------------------------------------------------\n");
|
|
printk("%s/%d just changed the state of lock:\n",
|
|
curr->comm, task_pid_nr(curr));
|
|
print_lock(this);
|
|
if (forwards)
|
|
printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
|
|
else
|
|
printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
|
|
print_lock_name(other);
|
|
printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
|
|
|
|
printk("\nother info that might help us debug this:\n");
|
|
lockdep_print_held_locks(curr);
|
|
|
|
printk("\nthe first lock's dependencies:\n");
|
|
print_lock_dependencies(this->class, 0);
|
|
|
|
printk("\nthe second lock's dependencies:\n");
|
|
print_lock_dependencies(other, 0);
|
|
|
|
printk("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Prove that in the forwards-direction subgraph starting at <this>
|
|
* there is no lock matching <mask>:
|
|
*/
|
|
static int
|
|
check_usage_forwards(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit bit, const char *irqclass)
|
|
{
|
|
int ret;
|
|
|
|
find_usage_bit = bit;
|
|
/* fills in <forwards_match> */
|
|
ret = find_usage_forwards(this->class, 0);
|
|
if (!ret || ret == 1)
|
|
return ret;
|
|
|
|
return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
|
|
}
|
|
|
|
/*
|
|
* Prove that in the backwards-direction subgraph starting at <this>
|
|
* there is no lock matching <mask>:
|
|
*/
|
|
static int
|
|
check_usage_backwards(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit bit, const char *irqclass)
|
|
{
|
|
int ret;
|
|
|
|
find_usage_bit = bit;
|
|
/* fills in <backwards_match> */
|
|
ret = find_usage_backwards(this->class, 0);
|
|
if (!ret || ret == 1)
|
|
return ret;
|
|
|
|
return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
|
|
}
|
|
|
|
void print_irqtrace_events(struct task_struct *curr)
|
|
{
|
|
printk("irq event stamp: %u\n", curr->irq_events);
|
|
printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
|
|
print_ip_sym(curr->hardirq_enable_ip);
|
|
printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
|
|
print_ip_sym(curr->hardirq_disable_ip);
|
|
printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
|
|
print_ip_sym(curr->softirq_enable_ip);
|
|
printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
|
|
print_ip_sym(curr->softirq_disable_ip);
|
|
}
|
|
|
|
static int hardirq_verbose(struct lock_class *class)
|
|
{
|
|
#if HARDIRQ_VERBOSE
|
|
return class_filter(class);
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
static int softirq_verbose(struct lock_class *class)
|
|
{
|
|
#if SOFTIRQ_VERBOSE
|
|
return class_filter(class);
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
#define STRICT_READ_CHECKS 1
|
|
|
|
static int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit new_bit)
|
|
{
|
|
int ret = 1;
|
|
|
|
switch(new_bit) {
|
|
case LOCK_USED_IN_HARDIRQ:
|
|
if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
|
|
return 0;
|
|
if (!valid_state(curr, this, new_bit,
|
|
LOCK_ENABLED_HARDIRQS_READ))
|
|
return 0;
|
|
/*
|
|
* just marked it hardirq-safe, check that this lock
|
|
* took no hardirq-unsafe lock in the past:
|
|
*/
|
|
if (!check_usage_forwards(curr, this,
|
|
LOCK_ENABLED_HARDIRQS, "hard"))
|
|
return 0;
|
|
#if STRICT_READ_CHECKS
|
|
/*
|
|
* just marked it hardirq-safe, check that this lock
|
|
* took no hardirq-unsafe-read lock in the past:
|
|
*/
|
|
if (!check_usage_forwards(curr, this,
|
|
LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
|
|
return 0;
|
|
#endif
|
|
if (hardirq_verbose(this->class))
|
|
ret = 2;
|
|
break;
|
|
case LOCK_USED_IN_SOFTIRQ:
|
|
if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
|
|
return 0;
|
|
if (!valid_state(curr, this, new_bit,
|
|
LOCK_ENABLED_SOFTIRQS_READ))
|
|
return 0;
|
|
/*
|
|
* just marked it softirq-safe, check that this lock
|
|
* took no softirq-unsafe lock in the past:
|
|
*/
|
|
if (!check_usage_forwards(curr, this,
|
|
LOCK_ENABLED_SOFTIRQS, "soft"))
|
|
return 0;
|
|
#if STRICT_READ_CHECKS
|
|
/*
|
|
* just marked it softirq-safe, check that this lock
|
|
* took no softirq-unsafe-read lock in the past:
|
|
*/
|
|
if (!check_usage_forwards(curr, this,
|
|
LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
|
|
return 0;
|
|
#endif
|
|
if (softirq_verbose(this->class))
|
|
ret = 2;
|
|
break;
|
|
case LOCK_USED_IN_HARDIRQ_READ:
|
|
if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
|
|
return 0;
|
|
/*
|
|
* just marked it hardirq-read-safe, check that this lock
|
|
* took no hardirq-unsafe lock in the past:
|
|
*/
|
|
if (!check_usage_forwards(curr, this,
|
|
LOCK_ENABLED_HARDIRQS, "hard"))
|
|
return 0;
|
|
if (hardirq_verbose(this->class))
|
|
ret = 2;
|
|
break;
|
|
case LOCK_USED_IN_SOFTIRQ_READ:
|
|
if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
|
|
return 0;
|
|
/*
|
|
* just marked it softirq-read-safe, check that this lock
|
|
* took no softirq-unsafe lock in the past:
|
|
*/
|
|
if (!check_usage_forwards(curr, this,
|
|
LOCK_ENABLED_SOFTIRQS, "soft"))
|
|
return 0;
|
|
if (softirq_verbose(this->class))
|
|
ret = 2;
|
|
break;
|
|
case LOCK_ENABLED_HARDIRQS:
|
|
if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
|
|
return 0;
|
|
if (!valid_state(curr, this, new_bit,
|
|
LOCK_USED_IN_HARDIRQ_READ))
|
|
return 0;
|
|
/*
|
|
* just marked it hardirq-unsafe, check that no hardirq-safe
|
|
* lock in the system ever took it in the past:
|
|
*/
|
|
if (!check_usage_backwards(curr, this,
|
|
LOCK_USED_IN_HARDIRQ, "hard"))
|
|
return 0;
|
|
#if STRICT_READ_CHECKS
|
|
/*
|
|
* just marked it hardirq-unsafe, check that no
|
|
* hardirq-safe-read lock in the system ever took
|
|
* it in the past:
|
|
*/
|
|
if (!check_usage_backwards(curr, this,
|
|
LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
|
|
return 0;
|
|
#endif
|
|
if (hardirq_verbose(this->class))
|
|
ret = 2;
|
|
break;
|
|
case LOCK_ENABLED_SOFTIRQS:
|
|
if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
|
|
return 0;
|
|
if (!valid_state(curr, this, new_bit,
|
|
LOCK_USED_IN_SOFTIRQ_READ))
|
|
return 0;
|
|
/*
|
|
* just marked it softirq-unsafe, check that no softirq-safe
|
|
* lock in the system ever took it in the past:
|
|
*/
|
|
if (!check_usage_backwards(curr, this,
|
|
LOCK_USED_IN_SOFTIRQ, "soft"))
|
|
return 0;
|
|
#if STRICT_READ_CHECKS
|
|
/*
|
|
* just marked it softirq-unsafe, check that no
|
|
* softirq-safe-read lock in the system ever took
|
|
* it in the past:
|
|
*/
|
|
if (!check_usage_backwards(curr, this,
|
|
LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
|
|
return 0;
|
|
#endif
|
|
if (softirq_verbose(this->class))
|
|
ret = 2;
|
|
break;
|
|
case LOCK_ENABLED_HARDIRQS_READ:
|
|
if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
|
|
return 0;
|
|
#if STRICT_READ_CHECKS
|
|
/*
|
|
* just marked it hardirq-read-unsafe, check that no
|
|
* hardirq-safe lock in the system ever took it in the past:
|
|
*/
|
|
if (!check_usage_backwards(curr, this,
|
|
LOCK_USED_IN_HARDIRQ, "hard"))
|
|
return 0;
|
|
#endif
|
|
if (hardirq_verbose(this->class))
|
|
ret = 2;
|
|
break;
|
|
case LOCK_ENABLED_SOFTIRQS_READ:
|
|
if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
|
|
return 0;
|
|
#if STRICT_READ_CHECKS
|
|
/*
|
|
* just marked it softirq-read-unsafe, check that no
|
|
* softirq-safe lock in the system ever took it in the past:
|
|
*/
|
|
if (!check_usage_backwards(curr, this,
|
|
LOCK_USED_IN_SOFTIRQ, "soft"))
|
|
return 0;
|
|
#endif
|
|
if (softirq_verbose(this->class))
|
|
ret = 2;
|
|
break;
|
|
default:
|
|
WARN_ON(1);
|
|
break;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Mark all held locks with a usage bit:
|
|
*/
|
|
static int
|
|
mark_held_locks(struct task_struct *curr, int hardirq)
|
|
{
|
|
enum lock_usage_bit usage_bit;
|
|
struct held_lock *hlock;
|
|
int i;
|
|
|
|
for (i = 0; i < curr->lockdep_depth; i++) {
|
|
hlock = curr->held_locks + i;
|
|
|
|
if (hardirq) {
|
|
if (hlock->read)
|
|
usage_bit = LOCK_ENABLED_HARDIRQS_READ;
|
|
else
|
|
usage_bit = LOCK_ENABLED_HARDIRQS;
|
|
} else {
|
|
if (hlock->read)
|
|
usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
|
|
else
|
|
usage_bit = LOCK_ENABLED_SOFTIRQS;
|
|
}
|
|
if (!mark_lock(curr, hlock, usage_bit))
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Debugging helper: via this flag we know that we are in
|
|
* 'early bootup code', and will warn about any invalid irqs-on event:
|
|
*/
|
|
static int early_boot_irqs_enabled;
|
|
|
|
void early_boot_irqs_off(void)
|
|
{
|
|
early_boot_irqs_enabled = 0;
|
|
}
|
|
|
|
void early_boot_irqs_on(void)
|
|
{
|
|
early_boot_irqs_enabled = 1;
|
|
}
|
|
|
|
/*
|
|
* Hardirqs will be enabled:
|
|
*/
|
|
void trace_hardirqs_on(void)
|
|
{
|
|
struct task_struct *curr = current;
|
|
unsigned long ip;
|
|
|
|
if (unlikely(!debug_locks || current->lockdep_recursion))
|
|
return;
|
|
|
|
if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
|
|
return;
|
|
|
|
if (unlikely(curr->hardirqs_enabled)) {
|
|
debug_atomic_inc(&redundant_hardirqs_on);
|
|
return;
|
|
}
|
|
/* we'll do an OFF -> ON transition: */
|
|
curr->hardirqs_enabled = 1;
|
|
ip = (unsigned long) __builtin_return_address(0);
|
|
|
|
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
|
|
return;
|
|
if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
|
|
return;
|
|
/*
|
|
* We are going to turn hardirqs on, so set the
|
|
* usage bit for all held locks:
|
|
*/
|
|
if (!mark_held_locks(curr, 1))
|
|
return;
|
|
/*
|
|
* If we have softirqs enabled, then set the usage
|
|
* bit for all held locks. (disabled hardirqs prevented
|
|
* this bit from being set before)
|
|
*/
|
|
if (curr->softirqs_enabled)
|
|
if (!mark_held_locks(curr, 0))
|
|
return;
|
|
|
|
curr->hardirq_enable_ip = ip;
|
|
curr->hardirq_enable_event = ++curr->irq_events;
|
|
debug_atomic_inc(&hardirqs_on_events);
|
|
}
|
|
|
|
EXPORT_SYMBOL(trace_hardirqs_on);
|
|
|
|
/*
|
|
* Hardirqs were disabled:
|
|
*/
|
|
void trace_hardirqs_off(void)
|
|
{
|
|
struct task_struct *curr = current;
|
|
|
|
if (unlikely(!debug_locks || current->lockdep_recursion))
|
|
return;
|
|
|
|
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
|
|
return;
|
|
|
|
if (curr->hardirqs_enabled) {
|
|
/*
|
|
* We have done an ON -> OFF transition:
|
|
*/
|
|
curr->hardirqs_enabled = 0;
|
|
curr->hardirq_disable_ip = _RET_IP_;
|
|
curr->hardirq_disable_event = ++curr->irq_events;
|
|
debug_atomic_inc(&hardirqs_off_events);
|
|
} else
|
|
debug_atomic_inc(&redundant_hardirqs_off);
|
|
}
|
|
|
|
EXPORT_SYMBOL(trace_hardirqs_off);
|
|
|
|
/*
|
|
* Softirqs will be enabled:
|
|
*/
|
|
void trace_softirqs_on(unsigned long ip)
|
|
{
|
|
struct task_struct *curr = current;
|
|
|
|
if (unlikely(!debug_locks))
|
|
return;
|
|
|
|
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
|
|
return;
|
|
|
|
if (curr->softirqs_enabled) {
|
|
debug_atomic_inc(&redundant_softirqs_on);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* We'll do an OFF -> ON transition:
|
|
*/
|
|
curr->softirqs_enabled = 1;
|
|
curr->softirq_enable_ip = ip;
|
|
curr->softirq_enable_event = ++curr->irq_events;
|
|
debug_atomic_inc(&softirqs_on_events);
|
|
/*
|
|
* We are going to turn softirqs on, so set the
|
|
* usage bit for all held locks, if hardirqs are
|
|
* enabled too:
|
|
*/
|
|
if (curr->hardirqs_enabled)
|
|
mark_held_locks(curr, 0);
|
|
}
|
|
|
|
/*
|
|
* Softirqs were disabled:
|
|
*/
|
|
void trace_softirqs_off(unsigned long ip)
|
|
{
|
|
struct task_struct *curr = current;
|
|
|
|
if (unlikely(!debug_locks))
|
|
return;
|
|
|
|
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
|
|
return;
|
|
|
|
if (curr->softirqs_enabled) {
|
|
/*
|
|
* We have done an ON -> OFF transition:
|
|
*/
|
|
curr->softirqs_enabled = 0;
|
|
curr->softirq_disable_ip = ip;
|
|
curr->softirq_disable_event = ++curr->irq_events;
|
|
debug_atomic_inc(&softirqs_off_events);
|
|
DEBUG_LOCKS_WARN_ON(!softirq_count());
|
|
} else
|
|
debug_atomic_inc(&redundant_softirqs_off);
|
|
}
|
|
|
|
static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
|
|
{
|
|
/*
|
|
* If non-trylock use in a hardirq or softirq context, then
|
|
* mark the lock as used in these contexts:
|
|
*/
|
|
if (!hlock->trylock) {
|
|
if (hlock->read) {
|
|
if (curr->hardirq_context)
|
|
if (!mark_lock(curr, hlock,
|
|
LOCK_USED_IN_HARDIRQ_READ))
|
|
return 0;
|
|
if (curr->softirq_context)
|
|
if (!mark_lock(curr, hlock,
|
|
LOCK_USED_IN_SOFTIRQ_READ))
|
|
return 0;
|
|
} else {
|
|
if (curr->hardirq_context)
|
|
if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
|
|
return 0;
|
|
if (curr->softirq_context)
|
|
if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
|
|
return 0;
|
|
}
|
|
}
|
|
if (!hlock->hardirqs_off) {
|
|
if (hlock->read) {
|
|
if (!mark_lock(curr, hlock,
|
|
LOCK_ENABLED_HARDIRQS_READ))
|
|
return 0;
|
|
if (curr->softirqs_enabled)
|
|
if (!mark_lock(curr, hlock,
|
|
LOCK_ENABLED_SOFTIRQS_READ))
|
|
return 0;
|
|
} else {
|
|
if (!mark_lock(curr, hlock,
|
|
LOCK_ENABLED_HARDIRQS))
|
|
return 0;
|
|
if (curr->softirqs_enabled)
|
|
if (!mark_lock(curr, hlock,
|
|
LOCK_ENABLED_SOFTIRQS))
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int separate_irq_context(struct task_struct *curr,
|
|
struct held_lock *hlock)
|
|
{
|
|
unsigned int depth = curr->lockdep_depth;
|
|
|
|
/*
|
|
* Keep track of points where we cross into an interrupt context:
|
|
*/
|
|
hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
|
|
curr->softirq_context;
|
|
if (depth) {
|
|
struct held_lock *prev_hlock;
|
|
|
|
prev_hlock = curr->held_locks + depth-1;
|
|
/*
|
|
* If we cross into another context, reset the
|
|
* hash key (this also prevents the checking and the
|
|
* adding of the dependency to 'prev'):
|
|
*/
|
|
if (prev_hlock->irq_context != hlock->irq_context)
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
#else
|
|
|
|
static inline
|
|
int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit new_bit)
|
|
{
|
|
WARN_ON(1);
|
|
return 1;
|
|
}
|
|
|
|
static inline int mark_irqflags(struct task_struct *curr,
|
|
struct held_lock *hlock)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
static inline int separate_irq_context(struct task_struct *curr,
|
|
struct held_lock *hlock)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
#endif
|
|
|
|
/*
|
|
* Mark a lock with a usage bit, and validate the state transition:
|
|
*/
|
|
static int mark_lock(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit new_bit)
|
|
{
|
|
unsigned int new_mask = 1 << new_bit, ret = 1;
|
|
|
|
/*
|
|
* If already set then do not dirty the cacheline,
|
|
* nor do any checks:
|
|
*/
|
|
if (likely(this->class->usage_mask & new_mask))
|
|
return 1;
|
|
|
|
if (!graph_lock())
|
|
return 0;
|
|
/*
|
|
* Make sure we didnt race:
|
|
*/
|
|
if (unlikely(this->class->usage_mask & new_mask)) {
|
|
graph_unlock();
|
|
return 1;
|
|
}
|
|
|
|
this->class->usage_mask |= new_mask;
|
|
|
|
if (!save_trace(this->class->usage_traces + new_bit))
|
|
return 0;
|
|
|
|
switch (new_bit) {
|
|
case LOCK_USED_IN_HARDIRQ:
|
|
case LOCK_USED_IN_SOFTIRQ:
|
|
case LOCK_USED_IN_HARDIRQ_READ:
|
|
case LOCK_USED_IN_SOFTIRQ_READ:
|
|
case LOCK_ENABLED_HARDIRQS:
|
|
case LOCK_ENABLED_SOFTIRQS:
|
|
case LOCK_ENABLED_HARDIRQS_READ:
|
|
case LOCK_ENABLED_SOFTIRQS_READ:
|
|
ret = mark_lock_irq(curr, this, new_bit);
|
|
if (!ret)
|
|
return 0;
|
|
break;
|
|
case LOCK_USED:
|
|
/*
|
|
* Add it to the global list of classes:
|
|
*/
|
|
list_add_tail_rcu(&this->class->lock_entry, &all_lock_classes);
|
|
debug_atomic_dec(&nr_unused_locks);
|
|
break;
|
|
default:
|
|
if (!debug_locks_off_graph_unlock())
|
|
return 0;
|
|
WARN_ON(1);
|
|
return 0;
|
|
}
|
|
|
|
graph_unlock();
|
|
|
|
/*
|
|
* We must printk outside of the graph_lock:
|
|
*/
|
|
if (ret == 2) {
|
|
printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
|
|
print_lock(this);
|
|
print_irqtrace_events(curr);
|
|
dump_stack();
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Initialize a lock instance's lock-class mapping info:
|
|
*/
|
|
void lockdep_init_map(struct lockdep_map *lock, const char *name,
|
|
struct lock_class_key *key, int subclass)
|
|
{
|
|
if (unlikely(!debug_locks))
|
|
return;
|
|
|
|
if (DEBUG_LOCKS_WARN_ON(!key))
|
|
return;
|
|
if (DEBUG_LOCKS_WARN_ON(!name))
|
|
return;
|
|
/*
|
|
* Sanity check, the lock-class key must be persistent:
|
|
*/
|
|
if (!static_obj(key)) {
|
|
printk("BUG: key %p not in .data!\n", key);
|
|
DEBUG_LOCKS_WARN_ON(1);
|
|
return;
|
|
}
|
|
lock->name = name;
|
|
lock->key = key;
|
|
lock->class_cache = NULL;
|
|
#ifdef CONFIG_LOCK_STAT
|
|
lock->cpu = raw_smp_processor_id();
|
|
#endif
|
|
if (subclass)
|
|
register_lock_class(lock, subclass, 1);
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(lockdep_init_map);
|
|
|
|
/*
|
|
* This gets called for every mutex_lock*()/spin_lock*() operation.
|
|
* We maintain the dependency maps and validate the locking attempt:
|
|
*/
|
|
static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
|
|
int trylock, int read, int check, int hardirqs_off,
|
|
unsigned long ip)
|
|
{
|
|
struct task_struct *curr = current;
|
|
struct lock_class *class = NULL;
|
|
struct held_lock *hlock;
|
|
unsigned int depth, id;
|
|
int chain_head = 0;
|
|
u64 chain_key;
|
|
|
|
if (!prove_locking)
|
|
check = 1;
|
|
|
|
if (unlikely(!debug_locks))
|
|
return 0;
|
|
|
|
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
|
|
return 0;
|
|
|
|
if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
|
|
debug_locks_off();
|
|
printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
|
|
printk("turning off the locking correctness validator.\n");
|
|
return 0;
|
|
}
|
|
|
|
if (!subclass)
|
|
class = lock->class_cache;
|
|
/*
|
|
* Not cached yet or subclass?
|
|
*/
|
|
if (unlikely(!class)) {
|
|
class = register_lock_class(lock, subclass, 0);
|
|
if (!class)
|
|
return 0;
|
|
}
|
|
debug_atomic_inc((atomic_t *)&class->ops);
|
|
if (very_verbose(class)) {
|
|
printk("\nacquire class [%p] %s", class->key, class->name);
|
|
if (class->name_version > 1)
|
|
printk("#%d", class->name_version);
|
|
printk("\n");
|
|
dump_stack();
|
|
}
|
|
|
|
/*
|
|
* Add the lock to the list of currently held locks.
|
|
* (we dont increase the depth just yet, up until the
|
|
* dependency checks are done)
|
|
*/
|
|
depth = curr->lockdep_depth;
|
|
if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
|
|
return 0;
|
|
|
|
hlock = curr->held_locks + depth;
|
|
|
|
hlock->class = class;
|
|
hlock->acquire_ip = ip;
|
|
hlock->instance = lock;
|
|
hlock->trylock = trylock;
|
|
hlock->read = read;
|
|
hlock->check = check;
|
|
hlock->hardirqs_off = hardirqs_off;
|
|
#ifdef CONFIG_LOCK_STAT
|
|
hlock->waittime_stamp = 0;
|
|
hlock->holdtime_stamp = sched_clock();
|
|
#endif
|
|
|
|
if (check == 2 && !mark_irqflags(curr, hlock))
|
|
return 0;
|
|
|
|
/* mark it as used: */
|
|
if (!mark_lock(curr, hlock, LOCK_USED))
|
|
return 0;
|
|
|
|
/*
|
|
* Calculate the chain hash: it's the combined hash of all the
|
|
* lock keys along the dependency chain. We save the hash value
|
|
* at every step so that we can get the current hash easily
|
|
* after unlock. The chain hash is then used to cache dependency
|
|
* results.
|
|
*
|
|
* The 'key ID' is what is the most compact key value to drive
|
|
* the hash, not class->key.
|
|
*/
|
|
id = class - lock_classes;
|
|
if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
|
|
return 0;
|
|
|
|
chain_key = curr->curr_chain_key;
|
|
if (!depth) {
|
|
if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
|
|
return 0;
|
|
chain_head = 1;
|
|
}
|
|
|
|
hlock->prev_chain_key = chain_key;
|
|
if (separate_irq_context(curr, hlock)) {
|
|
chain_key = 0;
|
|
chain_head = 1;
|
|
}
|
|
chain_key = iterate_chain_key(chain_key, id);
|
|
|
|
if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
|
|
return 0;
|
|
|
|
curr->curr_chain_key = chain_key;
|
|
curr->lockdep_depth++;
|
|
check_chain_key(curr);
|
|
#ifdef CONFIG_DEBUG_LOCKDEP
|
|
if (unlikely(!debug_locks))
|
|
return 0;
|
|
#endif
|
|
if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
|
|
debug_locks_off();
|
|
printk("BUG: MAX_LOCK_DEPTH too low!\n");
|
|
printk("turning off the locking correctness validator.\n");
|
|
return 0;
|
|
}
|
|
|
|
if (unlikely(curr->lockdep_depth > max_lockdep_depth))
|
|
max_lockdep_depth = curr->lockdep_depth;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int
|
|
print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
|
|
unsigned long ip)
|
|
{
|
|
if (!debug_locks_off())
|
|
return 0;
|
|
if (debug_locks_silent)
|
|
return 0;
|
|
|
|
printk("\n=====================================\n");
|
|
printk( "[ BUG: bad unlock balance detected! ]\n");
|
|
printk( "-------------------------------------\n");
|
|
printk("%s/%d is trying to release lock (",
|
|
curr->comm, task_pid_nr(curr));
|
|
print_lockdep_cache(lock);
|
|
printk(") at:\n");
|
|
print_ip_sym(ip);
|
|
printk("but there are no more locks to release!\n");
|
|
printk("\nother info that might help us debug this:\n");
|
|
lockdep_print_held_locks(curr);
|
|
|
|
printk("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Common debugging checks for both nested and non-nested unlock:
|
|
*/
|
|
static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
|
|
unsigned long ip)
|
|
{
|
|
if (unlikely(!debug_locks))
|
|
return 0;
|
|
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
|
|
return 0;
|
|
|
|
if (curr->lockdep_depth <= 0)
|
|
return print_unlock_inbalance_bug(curr, lock, ip);
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Remove the lock to the list of currently held locks in a
|
|
* potentially non-nested (out of order) manner. This is a
|
|
* relatively rare operation, as all the unlock APIs default
|
|
* to nested mode (which uses lock_release()):
|
|
*/
|
|
static int
|
|
lock_release_non_nested(struct task_struct *curr,
|
|
struct lockdep_map *lock, unsigned long ip)
|
|
{
|
|
struct held_lock *hlock, *prev_hlock;
|
|
unsigned int depth;
|
|
int i;
|
|
|
|
/*
|
|
* Check whether the lock exists in the current stack
|
|
* of held locks:
|
|
*/
|
|
depth = curr->lockdep_depth;
|
|
if (DEBUG_LOCKS_WARN_ON(!depth))
|
|
return 0;
|
|
|
|
prev_hlock = NULL;
|
|
for (i = depth-1; i >= 0; i--) {
|
|
hlock = curr->held_locks + i;
|
|
/*
|
|
* We must not cross into another context:
|
|
*/
|
|
if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
|
|
break;
|
|
if (hlock->instance == lock)
|
|
goto found_it;
|
|
prev_hlock = hlock;
|
|
}
|
|
return print_unlock_inbalance_bug(curr, lock, ip);
|
|
|
|
found_it:
|
|
lock_release_holdtime(hlock);
|
|
|
|
/*
|
|
* We have the right lock to unlock, 'hlock' points to it.
|
|
* Now we remove it from the stack, and add back the other
|
|
* entries (if any), recalculating the hash along the way:
|
|
*/
|
|
curr->lockdep_depth = i;
|
|
curr->curr_chain_key = hlock->prev_chain_key;
|
|
|
|
for (i++; i < depth; i++) {
|
|
hlock = curr->held_locks + i;
|
|
if (!__lock_acquire(hlock->instance,
|
|
hlock->class->subclass, hlock->trylock,
|
|
hlock->read, hlock->check, hlock->hardirqs_off,
|
|
hlock->acquire_ip))
|
|
return 0;
|
|
}
|
|
|
|
if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Remove the lock to the list of currently held locks - this gets
|
|
* called on mutex_unlock()/spin_unlock*() (or on a failed
|
|
* mutex_lock_interruptible()). This is done for unlocks that nest
|
|
* perfectly. (i.e. the current top of the lock-stack is unlocked)
|
|
*/
|
|
static int lock_release_nested(struct task_struct *curr,
|
|
struct lockdep_map *lock, unsigned long ip)
|
|
{
|
|
struct held_lock *hlock;
|
|
unsigned int depth;
|
|
|
|
/*
|
|
* Pop off the top of the lock stack:
|
|
*/
|
|
depth = curr->lockdep_depth - 1;
|
|
hlock = curr->held_locks + depth;
|
|
|
|
/*
|
|
* Is the unlock non-nested:
|
|
*/
|
|
if (hlock->instance != lock)
|
|
return lock_release_non_nested(curr, lock, ip);
|
|
curr->lockdep_depth--;
|
|
|
|
if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
|
|
return 0;
|
|
|
|
curr->curr_chain_key = hlock->prev_chain_key;
|
|
|
|
lock_release_holdtime(hlock);
|
|
|
|
#ifdef CONFIG_DEBUG_LOCKDEP
|
|
hlock->prev_chain_key = 0;
|
|
hlock->class = NULL;
|
|
hlock->acquire_ip = 0;
|
|
hlock->irq_context = 0;
|
|
#endif
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Remove the lock to the list of currently held locks - this gets
|
|
* called on mutex_unlock()/spin_unlock*() (or on a failed
|
|
* mutex_lock_interruptible()). This is done for unlocks that nest
|
|
* perfectly. (i.e. the current top of the lock-stack is unlocked)
|
|
*/
|
|
static void
|
|
__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
|
|
{
|
|
struct task_struct *curr = current;
|
|
|
|
if (!check_unlock(curr, lock, ip))
|
|
return;
|
|
|
|
if (nested) {
|
|
if (!lock_release_nested(curr, lock, ip))
|
|
return;
|
|
} else {
|
|
if (!lock_release_non_nested(curr, lock, ip))
|
|
return;
|
|
}
|
|
|
|
check_chain_key(curr);
|
|
}
|
|
|
|
/*
|
|
* Check whether we follow the irq-flags state precisely:
|
|
*/
|
|
static void check_flags(unsigned long flags)
|
|
{
|
|
#if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
|
|
if (!debug_locks)
|
|
return;
|
|
|
|
if (irqs_disabled_flags(flags)) {
|
|
if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
|
|
printk("possible reason: unannotated irqs-off.\n");
|
|
}
|
|
} else {
|
|
if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
|
|
printk("possible reason: unannotated irqs-on.\n");
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We dont accurately track softirq state in e.g.
|
|
* hardirq contexts (such as on 4KSTACKS), so only
|
|
* check if not in hardirq contexts:
|
|
*/
|
|
if (!hardirq_count()) {
|
|
if (softirq_count())
|
|
DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
|
|
else
|
|
DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
|
|
}
|
|
|
|
if (!debug_locks)
|
|
print_irqtrace_events(current);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* We are not always called with irqs disabled - do that here,
|
|
* and also avoid lockdep recursion:
|
|
*/
|
|
void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
|
|
int trylock, int read, int check, unsigned long ip)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (unlikely(!lock_stat && !prove_locking))
|
|
return;
|
|
|
|
if (unlikely(current->lockdep_recursion))
|
|
return;
|
|
|
|
raw_local_irq_save(flags);
|
|
check_flags(flags);
|
|
|
|
current->lockdep_recursion = 1;
|
|
__lock_acquire(lock, subclass, trylock, read, check,
|
|
irqs_disabled_flags(flags), ip);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(lock_acquire);
|
|
|
|
void lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (unlikely(!lock_stat && !prove_locking))
|
|
return;
|
|
|
|
if (unlikely(current->lockdep_recursion))
|
|
return;
|
|
|
|
raw_local_irq_save(flags);
|
|
check_flags(flags);
|
|
current->lockdep_recursion = 1;
|
|
__lock_release(lock, nested, ip);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(lock_release);
|
|
|
|
#ifdef CONFIG_LOCK_STAT
|
|
static int
|
|
print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
|
|
unsigned long ip)
|
|
{
|
|
if (!debug_locks_off())
|
|
return 0;
|
|
if (debug_locks_silent)
|
|
return 0;
|
|
|
|
printk("\n=================================\n");
|
|
printk( "[ BUG: bad contention detected! ]\n");
|
|
printk( "---------------------------------\n");
|
|
printk("%s/%d is trying to contend lock (",
|
|
curr->comm, task_pid_nr(curr));
|
|
print_lockdep_cache(lock);
|
|
printk(") at:\n");
|
|
print_ip_sym(ip);
|
|
printk("but there are no locks held!\n");
|
|
printk("\nother info that might help us debug this:\n");
|
|
lockdep_print_held_locks(curr);
|
|
|
|
printk("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void
|
|
__lock_contended(struct lockdep_map *lock, unsigned long ip)
|
|
{
|
|
struct task_struct *curr = current;
|
|
struct held_lock *hlock, *prev_hlock;
|
|
struct lock_class_stats *stats;
|
|
unsigned int depth;
|
|
int i, point;
|
|
|
|
depth = curr->lockdep_depth;
|
|
if (DEBUG_LOCKS_WARN_ON(!depth))
|
|
return;
|
|
|
|
prev_hlock = NULL;
|
|
for (i = depth-1; i >= 0; i--) {
|
|
hlock = curr->held_locks + i;
|
|
/*
|
|
* We must not cross into another context:
|
|
*/
|
|
if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
|
|
break;
|
|
if (hlock->instance == lock)
|
|
goto found_it;
|
|
prev_hlock = hlock;
|
|
}
|
|
print_lock_contention_bug(curr, lock, ip);
|
|
return;
|
|
|
|
found_it:
|
|
hlock->waittime_stamp = sched_clock();
|
|
|
|
point = lock_contention_point(hlock->class, ip);
|
|
|
|
stats = get_lock_stats(hlock->class);
|
|
if (point < ARRAY_SIZE(stats->contention_point))
|
|
stats->contention_point[i]++;
|
|
if (lock->cpu != smp_processor_id())
|
|
stats->bounces[bounce_contended + !!hlock->read]++;
|
|
put_lock_stats(stats);
|
|
}
|
|
|
|
static void
|
|
__lock_acquired(struct lockdep_map *lock)
|
|
{
|
|
struct task_struct *curr = current;
|
|
struct held_lock *hlock, *prev_hlock;
|
|
struct lock_class_stats *stats;
|
|
unsigned int depth;
|
|
u64 now;
|
|
s64 waittime = 0;
|
|
int i, cpu;
|
|
|
|
depth = curr->lockdep_depth;
|
|
if (DEBUG_LOCKS_WARN_ON(!depth))
|
|
return;
|
|
|
|
prev_hlock = NULL;
|
|
for (i = depth-1; i >= 0; i--) {
|
|
hlock = curr->held_locks + i;
|
|
/*
|
|
* We must not cross into another context:
|
|
*/
|
|
if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
|
|
break;
|
|
if (hlock->instance == lock)
|
|
goto found_it;
|
|
prev_hlock = hlock;
|
|
}
|
|
print_lock_contention_bug(curr, lock, _RET_IP_);
|
|
return;
|
|
|
|
found_it:
|
|
cpu = smp_processor_id();
|
|
if (hlock->waittime_stamp) {
|
|
now = sched_clock();
|
|
waittime = now - hlock->waittime_stamp;
|
|
hlock->holdtime_stamp = now;
|
|
}
|
|
|
|
stats = get_lock_stats(hlock->class);
|
|
if (waittime) {
|
|
if (hlock->read)
|
|
lock_time_inc(&stats->read_waittime, waittime);
|
|
else
|
|
lock_time_inc(&stats->write_waittime, waittime);
|
|
}
|
|
if (lock->cpu != cpu)
|
|
stats->bounces[bounce_acquired + !!hlock->read]++;
|
|
put_lock_stats(stats);
|
|
|
|
lock->cpu = cpu;
|
|
}
|
|
|
|
void lock_contended(struct lockdep_map *lock, unsigned long ip)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (unlikely(!lock_stat))
|
|
return;
|
|
|
|
if (unlikely(current->lockdep_recursion))
|
|
return;
|
|
|
|
raw_local_irq_save(flags);
|
|
check_flags(flags);
|
|
current->lockdep_recursion = 1;
|
|
__lock_contended(lock, ip);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(lock_contended);
|
|
|
|
void lock_acquired(struct lockdep_map *lock)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (unlikely(!lock_stat))
|
|
return;
|
|
|
|
if (unlikely(current->lockdep_recursion))
|
|
return;
|
|
|
|
raw_local_irq_save(flags);
|
|
check_flags(flags);
|
|
current->lockdep_recursion = 1;
|
|
__lock_acquired(lock);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(lock_acquired);
|
|
#endif
|
|
|
|
/*
|
|
* Used by the testsuite, sanitize the validator state
|
|
* after a simulated failure:
|
|
*/
|
|
|
|
void lockdep_reset(void)
|
|
{
|
|
unsigned long flags;
|
|
int i;
|
|
|
|
raw_local_irq_save(flags);
|
|
current->curr_chain_key = 0;
|
|
current->lockdep_depth = 0;
|
|
current->lockdep_recursion = 0;
|
|
memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
|
|
nr_hardirq_chains = 0;
|
|
nr_softirq_chains = 0;
|
|
nr_process_chains = 0;
|
|
debug_locks = 1;
|
|
for (i = 0; i < CHAINHASH_SIZE; i++)
|
|
INIT_LIST_HEAD(chainhash_table + i);
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
|
|
static void zap_class(struct lock_class *class)
|
|
{
|
|
int i;
|
|
|
|
/*
|
|
* Remove all dependencies this lock is
|
|
* involved in:
|
|
*/
|
|
for (i = 0; i < nr_list_entries; i++) {
|
|
if (list_entries[i].class == class)
|
|
list_del_rcu(&list_entries[i].entry);
|
|
}
|
|
/*
|
|
* Unhash the class and remove it from the all_lock_classes list:
|
|
*/
|
|
list_del_rcu(&class->hash_entry);
|
|
list_del_rcu(&class->lock_entry);
|
|
|
|
}
|
|
|
|
static inline int within(void *addr, void *start, unsigned long size)
|
|
{
|
|
return addr >= start && addr < start + size;
|
|
}
|
|
|
|
void lockdep_free_key_range(void *start, unsigned long size)
|
|
{
|
|
struct lock_class *class, *next;
|
|
struct list_head *head;
|
|
unsigned long flags;
|
|
int i;
|
|
int locked;
|
|
|
|
raw_local_irq_save(flags);
|
|
locked = graph_lock();
|
|
|
|
/*
|
|
* Unhash all classes that were created by this module:
|
|
*/
|
|
for (i = 0; i < CLASSHASH_SIZE; i++) {
|
|
head = classhash_table + i;
|
|
if (list_empty(head))
|
|
continue;
|
|
list_for_each_entry_safe(class, next, head, hash_entry)
|
|
if (within(class->key, start, size))
|
|
zap_class(class);
|
|
}
|
|
|
|
if (locked)
|
|
graph_unlock();
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
|
|
void lockdep_reset_lock(struct lockdep_map *lock)
|
|
{
|
|
struct lock_class *class, *next;
|
|
struct list_head *head;
|
|
unsigned long flags;
|
|
int i, j;
|
|
int locked;
|
|
|
|
raw_local_irq_save(flags);
|
|
|
|
/*
|
|
* Remove all classes this lock might have:
|
|
*/
|
|
for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
|
|
/*
|
|
* If the class exists we look it up and zap it:
|
|
*/
|
|
class = look_up_lock_class(lock, j);
|
|
if (class)
|
|
zap_class(class);
|
|
}
|
|
/*
|
|
* Debug check: in the end all mapped classes should
|
|
* be gone.
|
|
*/
|
|
locked = graph_lock();
|
|
for (i = 0; i < CLASSHASH_SIZE; i++) {
|
|
head = classhash_table + i;
|
|
if (list_empty(head))
|
|
continue;
|
|
list_for_each_entry_safe(class, next, head, hash_entry) {
|
|
if (unlikely(class == lock->class_cache)) {
|
|
if (debug_locks_off_graph_unlock())
|
|
WARN_ON(1);
|
|
goto out_restore;
|
|
}
|
|
}
|
|
}
|
|
if (locked)
|
|
graph_unlock();
|
|
|
|
out_restore:
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
|
|
void lockdep_init(void)
|
|
{
|
|
int i;
|
|
|
|
/*
|
|
* Some architectures have their own start_kernel()
|
|
* code which calls lockdep_init(), while we also
|
|
* call lockdep_init() from the start_kernel() itself,
|
|
* and we want to initialize the hashes only once:
|
|
*/
|
|
if (lockdep_initialized)
|
|
return;
|
|
|
|
for (i = 0; i < CLASSHASH_SIZE; i++)
|
|
INIT_LIST_HEAD(classhash_table + i);
|
|
|
|
for (i = 0; i < CHAINHASH_SIZE; i++)
|
|
INIT_LIST_HEAD(chainhash_table + i);
|
|
|
|
lockdep_initialized = 1;
|
|
}
|
|
|
|
void __init lockdep_info(void)
|
|
{
|
|
printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
|
|
|
|
printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
|
|
printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
|
|
printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
|
|
printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
|
|
printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
|
|
printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
|
|
printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
|
|
|
|
printk(" memory used by lock dependency info: %lu kB\n",
|
|
(sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
|
|
sizeof(struct list_head) * CLASSHASH_SIZE +
|
|
sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
|
|
sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
|
|
sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
|
|
|
|
printk(" per task-struct memory footprint: %lu bytes\n",
|
|
sizeof(struct held_lock) * MAX_LOCK_DEPTH);
|
|
|
|
#ifdef CONFIG_DEBUG_LOCKDEP
|
|
if (lockdep_init_error) {
|
|
printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
|
|
printk("Call stack leading to lockdep invocation was:\n");
|
|
print_stack_trace(&lockdep_init_trace, 0);
|
|
}
|
|
#endif
|
|
}
|
|
|
|
static void
|
|
print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
|
|
const void *mem_to, struct held_lock *hlock)
|
|
{
|
|
if (!debug_locks_off())
|
|
return;
|
|
if (debug_locks_silent)
|
|
return;
|
|
|
|
printk("\n=========================\n");
|
|
printk( "[ BUG: held lock freed! ]\n");
|
|
printk( "-------------------------\n");
|
|
printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
|
|
curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
|
|
print_lock(hlock);
|
|
lockdep_print_held_locks(curr);
|
|
|
|
printk("\nstack backtrace:\n");
|
|
dump_stack();
|
|
}
|
|
|
|
static inline int not_in_range(const void* mem_from, unsigned long mem_len,
|
|
const void* lock_from, unsigned long lock_len)
|
|
{
|
|
return lock_from + lock_len <= mem_from ||
|
|
mem_from + mem_len <= lock_from;
|
|
}
|
|
|
|
/*
|
|
* Called when kernel memory is freed (or unmapped), or if a lock
|
|
* is destroyed or reinitialized - this code checks whether there is
|
|
* any held lock in the memory range of <from> to <to>:
|
|
*/
|
|
void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
|
|
{
|
|
struct task_struct *curr = current;
|
|
struct held_lock *hlock;
|
|
unsigned long flags;
|
|
int i;
|
|
|
|
if (unlikely(!debug_locks))
|
|
return;
|
|
|
|
local_irq_save(flags);
|
|
for (i = 0; i < curr->lockdep_depth; i++) {
|
|
hlock = curr->held_locks + i;
|
|
|
|
if (not_in_range(mem_from, mem_len, hlock->instance,
|
|
sizeof(*hlock->instance)))
|
|
continue;
|
|
|
|
print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
|
|
break;
|
|
}
|
|
local_irq_restore(flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
|
|
|
|
static void print_held_locks_bug(struct task_struct *curr)
|
|
{
|
|
if (!debug_locks_off())
|
|
return;
|
|
if (debug_locks_silent)
|
|
return;
|
|
|
|
printk("\n=====================================\n");
|
|
printk( "[ BUG: lock held at task exit time! ]\n");
|
|
printk( "-------------------------------------\n");
|
|
printk("%s/%d is exiting with locks still held!\n",
|
|
curr->comm, task_pid_nr(curr));
|
|
lockdep_print_held_locks(curr);
|
|
|
|
printk("\nstack backtrace:\n");
|
|
dump_stack();
|
|
}
|
|
|
|
void debug_check_no_locks_held(struct task_struct *task)
|
|
{
|
|
if (unlikely(task->lockdep_depth > 0))
|
|
print_held_locks_bug(task);
|
|
}
|
|
|
|
void debug_show_all_locks(void)
|
|
{
|
|
struct task_struct *g, *p;
|
|
int count = 10;
|
|
int unlock = 1;
|
|
|
|
if (unlikely(!debug_locks)) {
|
|
printk("INFO: lockdep is turned off.\n");
|
|
return;
|
|
}
|
|
printk("\nShowing all locks held in the system:\n");
|
|
|
|
/*
|
|
* Here we try to get the tasklist_lock as hard as possible,
|
|
* if not successful after 2 seconds we ignore it (but keep
|
|
* trying). This is to enable a debug printout even if a
|
|
* tasklist_lock-holding task deadlocks or crashes.
|
|
*/
|
|
retry:
|
|
if (!read_trylock(&tasklist_lock)) {
|
|
if (count == 10)
|
|
printk("hm, tasklist_lock locked, retrying... ");
|
|
if (count) {
|
|
count--;
|
|
printk(" #%d", 10-count);
|
|
mdelay(200);
|
|
goto retry;
|
|
}
|
|
printk(" ignoring it.\n");
|
|
unlock = 0;
|
|
}
|
|
if (count != 10)
|
|
printk(" locked it.\n");
|
|
|
|
do_each_thread(g, p) {
|
|
/*
|
|
* It's not reliable to print a task's held locks
|
|
* if it's not sleeping (or if it's not the current
|
|
* task):
|
|
*/
|
|
if (p->state == TASK_RUNNING && p != current)
|
|
continue;
|
|
if (p->lockdep_depth)
|
|
lockdep_print_held_locks(p);
|
|
if (!unlock)
|
|
if (read_trylock(&tasklist_lock))
|
|
unlock = 1;
|
|
} while_each_thread(g, p);
|
|
|
|
printk("\n");
|
|
printk("=============================================\n\n");
|
|
|
|
if (unlock)
|
|
read_unlock(&tasklist_lock);
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(debug_show_all_locks);
|
|
|
|
void debug_show_held_locks(struct task_struct *task)
|
|
{
|
|
if (unlikely(!debug_locks)) {
|
|
printk("INFO: lockdep is turned off.\n");
|
|
return;
|
|
}
|
|
lockdep_print_held_locks(task);
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(debug_show_held_locks);
|
|
|
|
void lockdep_sys_exit(void)
|
|
{
|
|
struct task_struct *curr = current;
|
|
|
|
if (unlikely(curr->lockdep_depth)) {
|
|
if (!debug_locks_off())
|
|
return;
|
|
printk("\n================================================\n");
|
|
printk( "[ BUG: lock held when returning to user space! ]\n");
|
|
printk( "------------------------------------------------\n");
|
|
printk("%s/%d is leaving the kernel with locks still held!\n",
|
|
curr->comm, curr->pid);
|
|
lockdep_print_held_locks(curr);
|
|
}
|
|
}
|