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Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus 

* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
  stop_machine: fix up ftrace.c
  stop_machine: Wean existing callers off stop_machine_run()
  stop_machine(): stop_machine_run() changed to use cpu mask
  Hotplug CPU: don't check cpu_online after take_cpu_down
  Simplify stop_machine
  stop_machine: add ALL_CPUS option
  module: fix build warning with !CONFIG_KALLSYMS
This commit is contained in:
Linus Torvalds 2008-07-28 08:37:46 -07:00
parent 58f250714f 784e2d7600
commit 37eaf8c746
9 changed files with 211 additions and 226 deletions
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6
arch/s390/kernel/kprobes.c
View File

@ -197,7 +197,7 @@ void __kprobes arch_arm_kprobe(struct kprobe *p)
args.new = BREAKPOINT_INSTRUCTION;
kcb->kprobe_status = KPROBE_SWAP_INST;
stop_machine_run(swap_instruction, &args, NR_CPUS);
stop_machine(swap_instruction, &args, NULL);
kcb->kprobe_status = status;
}
@ -212,7 +212,7 @@ void __kprobes arch_disarm_kprobe(struct kprobe *p)
args.new = p->opcode;
kcb->kprobe_status = KPROBE_SWAP_INST;
stop_machine_run(swap_instruction, &args, NR_CPUS);
stop_machine(swap_instruction, &args, NULL);
kcb->kprobe_status = status;
}
@ -331,7 +331,7 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
* No kprobe at this address. The fault has not been
* caused by a kprobe breakpoint. The race of breakpoint
* vs. kprobe remove does not exist because on s390 we
* use stop_machine_run to arm/disarm the breakpoints.
* use stop_machine to arm/disarm the breakpoints.
*/
goto no_kprobe;

6
drivers/char/hw_random/intel-rng.c
View File

@ -241,7 +241,7 @@ static int __init intel_rng_hw_init(void *_intel_rng_hw)
struct intel_rng_hw *intel_rng_hw = _intel_rng_hw;
u8 mfc, dvc;
/* interrupts disabled in stop_machine_run call */
/* interrupts disabled in stop_machine call */
if (!(intel_rng_hw->fwh_dec_en1_val & FWH_F8_EN_MASK))
pci_write_config_byte(intel_rng_hw->dev,
@ -365,10 +365,10 @@ static int __init mod_init(void)
* location with the Read ID command, all activity on the system
* must be stopped until the state is back to normal.
*
* Use stop_machine_run because IPIs can be blocked by disabling
* Use stop_machine because IPIs can be blocked by disabling
* interrupts.
*/
err = stop_machine_run(intel_rng_hw_init, intel_rng_hw, NR_CPUS);
err = stop_machine(intel_rng_hw_init, intel_rng_hw, NULL);
pci_dev_put(dev);
iounmap(intel_rng_hw->mem);
kfree(intel_rng_hw);

50
include/linux/stop_machine.h
View File

@ -5,41 +5,43 @@
(and more). So the "read" side to such a lock is anything which
diables preeempt. */
#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <asm/system.h>
#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
/* Deprecated, but useful for transition. */
#define ALL_CPUS ~0U
/**
* stop_machine_run: freeze the machine on all CPUs and run this function
* stop_machine: freeze the machine on all CPUs and run this function
* @fn: the function to run
* @data: the data ptr for the @fn()
* @cpu: the cpu to run @fn() on (or any, if @cpu == NR_CPUS.
* @cpus: the cpus to run the @fn() on (NULL = any online cpu)
*
* Description: This causes a thread to be scheduled on every other cpu,
* each of which disables interrupts, and finally interrupts are disabled
* on the current CPU. The result is that noone is holding a spinlock
* or inside any other preempt-disabled region when @fn() runs.
* Description: This causes a thread to be scheduled on every cpu,
* each of which disables interrupts. The result is that noone is
* holding a spinlock or inside any other preempt-disabled region when
* @fn() runs.
*
* This can be thought of as a very heavy write lock, equivalent to
* grabbing every spinlock in the kernel. */
int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu);
int stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus);
/**
* __stop_machine_run: freeze the machine on all CPUs and run this function
* __stop_machine: freeze the machine on all CPUs and run this function
* @fn: the function to run
* @data: the data ptr for the @fn
* @cpu: the cpu to run @fn on (or any, if @cpu == NR_CPUS.
* @cpus: the cpus to run the @fn() on (NULL = any online cpu)
*
* Description: This is a special version of the above, which returns the
* thread which has run @fn(): kthread_stop will return the return value
* of @fn(). Used by hotplug cpu.
* Description: This is a special version of the above, which assumes cpus
* won't come or go while it's being called. Used by hotplug cpu.
*/
struct task_struct *__stop_machine_run(int (*fn)(void *), void *data,
unsigned int cpu);
int __stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus);
#else
static inline int stop_machine_run(int (*fn)(void *), void *data,
unsigned int cpu)
static inline int stop_machine(int (*fn)(void *), void *data,
const cpumask_t *cpus)
{
int ret;
local_irq_disable();
@ -48,4 +50,18 @@ static inline int stop_machine_run(int (*fn)(void *), void *data,
return ret;
}
#endif /* CONFIG_SMP */
static inline int __deprecated stop_machine_run(int (*fn)(void *), void *data,
unsigned int cpu)
{
/* If they don't care which cpu fn runs on, just pick one. */
if (cpu == NR_CPUS)
return stop_machine(fn, data, NULL);
else if (cpu == ~0U)
return stop_machine(fn, data, &cpu_possible_map);
else {
cpumask_t cpus = cpumask_of_cpu(cpu);
return stop_machine(fn, data, &cpus);
}
}
#endif /* _LINUX_STOP_MACHINE */

16
kernel/cpu.c
View File

@ -216,7 +216,6 @@ static int __ref take_cpu_down(void *_param)
static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
{
int err, nr_calls = 0;
struct task_struct *p;
cpumask_t old_allowed, tmp;
void *hcpu = (void *)(long)cpu;
unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
@ -249,21 +248,18 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
cpus_setall(tmp);
cpu_clear(cpu, tmp);
set_cpus_allowed_ptr(current, &tmp);
tmp = cpumask_of_cpu(cpu);
p = __stop_machine_run(take_cpu_down, &tcd_param, cpu);
if (IS_ERR(p) || cpu_online(cpu)) {
err = __stop_machine(take_cpu_down, &tcd_param, &tmp);
if (err) {
/* CPU didn't die: tell everyone. Can't complain. */
if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
hcpu) == NOTIFY_BAD)
BUG();
if (IS_ERR(p)) {
err = PTR_ERR(p);
goto out_allowed;
}
goto out_thread;
goto out_allowed;
}
BUG_ON(cpu_online(cpu));
/* Wait for it to sleep (leaving idle task). */
while (!idle_cpu(cpu))
@ -279,8 +275,6 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
check_for_tasks(cpu);
out_thread:
err = kthread_stop(p);
out_allowed:
set_cpus_allowed_ptr(current, &old_allowed);
out_release:

33
kernel/module.c
View File

@ -325,18 +325,6 @@ static unsigned long find_symbol(const char *name,
return -ENOENT;
}
/* lookup symbol in given range of kernel_symbols */
static const struct kernel_symbol *lookup_symbol(const char *name,
const struct kernel_symbol *start,
const struct kernel_symbol *stop)
{
const struct kernel_symbol *ks = start;
for (; ks < stop; ks++)
if (strcmp(ks->name, name) == 0)
return ks;
return NULL;
}
/* Search for module by name: must hold module_mutex. */
static struct module *find_module(const char *name)
{
@ -690,7 +678,7 @@ static int try_stop_module(struct module *mod, int flags, int *forced)
if (flags & O_NONBLOCK) {
struct stopref sref = { mod, flags, forced };
return stop_machine_run(__try_stop_module, &sref, NR_CPUS);
return stop_machine(__try_stop_module, &sref, NULL);
} else {
/* We don't need to stop the machine for this. */
mod->state = MODULE_STATE_GOING;
@ -1428,7 +1416,7 @@ static int __unlink_module(void *_mod)
static void free_module(struct module *mod)
{
/* Delete from various lists */
stop_machine_run(__unlink_module, mod, NR_CPUS);
stop_machine(__unlink_module, mod, NULL);
remove_notes_attrs(mod);
remove_sect_attrs(mod);
mod_kobject_remove(mod);
@ -1703,6 +1691,19 @@ static void setup_modinfo(struct module *mod, Elf_Shdr *sechdrs,
}
#ifdef CONFIG_KALLSYMS
/* lookup symbol in given range of kernel_symbols */
static const struct kernel_symbol *lookup_symbol(const char *name,
const struct kernel_symbol *start,
const struct kernel_symbol *stop)
{
const struct kernel_symbol *ks = start;
for (; ks < stop; ks++)
if (strcmp(ks->name, name) == 0)
return ks;
return NULL;
}
static int is_exported(const char *name, const struct module *mod)
{
if (!mod && lookup_symbol(name, __start___ksymtab, __stop___ksymtab))
@ -2196,7 +2197,7 @@ static struct module *load_module(void __user *umod,
/* Now sew it into the lists so we can get lockdep and oops
* info during argument parsing. Noone should access us, since
* strong_try_module_get() will fail. */
stop_machine_run(__link_module, mod, NR_CPUS);
stop_machine(__link_module, mod, NULL);
/* Size of section 0 is 0, so this works well if no params */
err = parse_args(mod->name, mod->args,
@ -2230,7 +2231,7 @@ static struct module *load_module(void __user *umod,
return mod;
unlink:
stop_machine_run(__unlink_module, mod, NR_CPUS);
stop_machine(__unlink_module, mod, NULL);
module_arch_cleanup(mod);
cleanup:
kobject_del(&mod->mkobj.kobj);

4
kernel/rcuclassic.c
View File

@ -91,8 +91,8 @@ static void force_quiescent_state(struct rcu_data *rdp,
* rdp->cpu is the current cpu.
*
* cpu_online_map is updated by the _cpu_down()
* using stop_machine_run(). Since we're in irqs disabled
* section, stop_machine_run() is not exectuting, hence
* using __stop_machine(). Since we're in irqs disabled
* section, __stop_machine() is not exectuting, hence
* the cpu_online_map is stable.
*
* However, a cpu might have been offlined _just_ before

312
kernel/stop_machine.c
View File

@ -1,4 +1,4 @@
/* Copyright 2005 Rusty Russell rusty@rustcorp.com.au IBM Corporation.
/* Copyright 2008, 2005 Rusty Russell rusty@rustcorp.com.au IBM Corporation.
* GPL v2 and any later version.
*/
#include <linux/cpu.h>
@ -13,204 +13,178 @@
#include <asm/atomic.h>
#include <asm/uaccess.h>
/* Since we effect priority and affinity (both of which are visible
* to, and settable by outside processes) we do indirection via a
* kthread. */
/* Thread to stop each CPU in user context. */
/* This controls the threads on each CPU. */
enum stopmachine_state {
STOPMACHINE_WAIT,
/* Dummy starting state for thread. */
STOPMACHINE_NONE,
/* Awaiting everyone to be scheduled. */
STOPMACHINE_PREPARE,
/* Disable interrupts. */
STOPMACHINE_DISABLE_IRQ,
/* Run the function */
STOPMACHINE_RUN,
/* Exit */
STOPMACHINE_EXIT,
};
static enum stopmachine_state stopmachine_state;
static unsigned int stopmachine_num_threads;
static atomic_t stopmachine_thread_ack;
static int stopmachine(void *cpu)
{
int irqs_disabled = 0;
int prepared = 0;
cpumask_of_cpu_ptr(cpumask, (int)(long)cpu);
set_cpus_allowed_ptr(current, cpumask);
/* Ack: we are alive */
smp_mb(); /* Theoretically the ack = 0 might not be on this CPU yet. */
atomic_inc(&stopmachine_thread_ack);
/* Simple state machine */
while (stopmachine_state != STOPMACHINE_EXIT) {
if (stopmachine_state == STOPMACHINE_DISABLE_IRQ
&& !irqs_disabled) {
local_irq_disable();
hard_irq_disable();
irqs_disabled = 1;
/* Ack: irqs disabled. */
smp_mb(); /* Must read state first. */
atomic_inc(&stopmachine_thread_ack);
} else if (stopmachine_state == STOPMACHINE_PREPARE
&& !prepared) {
/* Everyone is in place, hold CPU. */
preempt_disable();
prepared = 1;
smp_mb(); /* Must read state first. */
atomic_inc(&stopmachine_thread_ack);
}
/* Yield in first stage: migration threads need to
* help our sisters onto their CPUs. */
if (!prepared && !irqs_disabled)
yield();
cpu_relax();
}
/* Ack: we are exiting. */
smp_mb(); /* Must read state first. */
atomic_inc(&stopmachine_thread_ack);
if (irqs_disabled)
local_irq_enable();
if (prepared)
preempt_enable();
return 0;
}
/* Change the thread state */
static void stopmachine_set_state(enum stopmachine_state state)
{
atomic_set(&stopmachine_thread_ack, 0);
smp_wmb();
stopmachine_state = state;
while (atomic_read(&stopmachine_thread_ack) != stopmachine_num_threads)
cpu_relax();
}
static int stop_machine(void)
{
int i, ret = 0;
atomic_set(&stopmachine_thread_ack, 0);
stopmachine_num_threads = 0;
stopmachine_state = STOPMACHINE_WAIT;
for_each_online_cpu(i) {
if (i == raw_smp_processor_id())
continue;
ret = kernel_thread(stopmachine, (void *)(long)i,CLONE_KERNEL);
if (ret < 0)
break;
stopmachine_num_threads++;
}
/* Wait for them all to come to life. */
while (atomic_read(&stopmachine_thread_ack) != stopmachine_num_threads) {
yield();
cpu_relax();
}
/* If some failed, kill them all. */
if (ret < 0) {
stopmachine_set_state(STOPMACHINE_EXIT);
return ret;
}
/* Now they are all started, make them hold the CPUs, ready. */
preempt_disable();
stopmachine_set_state(STOPMACHINE_PREPARE);
/* Make them disable irqs. */
local_irq_disable();
hard_irq_disable();
stopmachine_set_state(STOPMACHINE_DISABLE_IRQ);
return 0;
}
static void restart_machine(void)
{
stopmachine_set_state(STOPMACHINE_EXIT);
local_irq_enable();
preempt_enable_no_resched();
}
static enum stopmachine_state state;
struct stop_machine_data {
int (*fn)(void *);
void *data;
struct completion done;
int fnret;
};
static int do_stop(void *_smdata)
/* Like num_online_cpus(), but hotplug cpu uses us, so we need this. */
static unsigned int num_threads;
static atomic_t thread_ack;
static struct completion finished;
static DEFINE_MUTEX(lock);
static void set_state(enum stopmachine_state newstate)
{
struct stop_machine_data *smdata = _smdata;
int ret;
ret = stop_machine();
if (ret == 0) {
ret = smdata->fn(smdata->data);
restart_machine();
}
/* We're done: you can kthread_stop us now */
complete(&smdata->done);
/* Wait for kthread_stop */
set_current_state(TASK_INTERRUPTIBLE);
while (!kthread_should_stop()) {
schedule();
set_current_state(TASK_INTERRUPTIBLE);
}
__set_current_state(TASK_RUNNING);
return ret;
/* Reset ack counter. */
atomic_set(&thread_ack, num_threads);
smp_wmb();
state = newstate;
}
struct task_struct *__stop_machine_run(int (*fn)(void *), void *data,
unsigned int cpu)
/* Last one to ack a state moves to the next state. */
static void ack_state(void)
{
static DEFINE_MUTEX(stopmachine_mutex);
struct stop_machine_data smdata;
struct task_struct *p;
if (atomic_dec_and_test(&thread_ack)) {
/* If we're the last one to ack the EXIT, we're finished. */
if (state == STOPMACHINE_EXIT)
complete(&finished);
else
set_state(state + 1);
}
}
smdata.fn = fn;
smdata.data = data;
init_completion(&smdata.done);
/* This is the actual thread which stops the CPU. It exits by itself rather
* than waiting for kthread_stop(), because it's easier for hotplug CPU. */
static int stop_cpu(struct stop_machine_data *smdata)
{
enum stopmachine_state curstate = STOPMACHINE_NONE;
int uninitialized_var(ret);
mutex_lock(&stopmachine_mutex);
/* Simple state machine */
do {
/* Chill out and ensure we re-read stopmachine_state. */
cpu_relax();
if (state != curstate) {
curstate = state;
switch (curstate) {
case STOPMACHINE_DISABLE_IRQ:
local_irq_disable();
hard_irq_disable();
break;
case STOPMACHINE_RUN:
/* |= allows error detection if functions on
* multiple CPUs. */
smdata->fnret |= smdata->fn(smdata->data);
break;
default:
break;
}
ack_state();
}
} while (curstate != STOPMACHINE_EXIT);
/* If they don't care which CPU fn runs on, bind to any online one. */
if (cpu == NR_CPUS)
cpu = raw_smp_processor_id();
local_irq_enable();
do_exit(0);
}
p = kthread_create(do_stop, &smdata, "kstopmachine");
if (!IS_ERR(p)) {
/* Callback for CPUs which aren't supposed to do anything. */
static int chill(void *unused)
{
return 0;
}
int __stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus)
{
int i, err;
struct stop_machine_data active, idle;
struct task_struct **threads;
active.fn = fn;
active.data = data;
active.fnret = 0;
idle.fn = chill;
idle.data = NULL;
/* This could be too big for stack on large machines. */
threads = kcalloc(NR_CPUS, sizeof(threads[0]), GFP_KERNEL);
if (!threads)
return -ENOMEM;
/* Set up initial state. */
mutex_lock(&lock);
init_completion(&finished);
num_threads = num_online_cpus();
set_state(STOPMACHINE_PREPARE);
for_each_online_cpu(i) {
struct stop_machine_data *smdata = &idle;
struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
/* One high-prio thread per cpu. We'll do this one. */
sched_setscheduler_nocheck(p, SCHED_FIFO, &param);
kthread_bind(p, cpu);
wake_up_process(p);
wait_for_completion(&smdata.done);
if (!cpus) {
if (i == first_cpu(cpu_online_map))
smdata = &active;
} else {
if (cpu_isset(i, *cpus))
smdata = &active;
}
threads[i] = kthread_create((void *)stop_cpu, smdata, "kstop%u",
i);
if (IS_ERR(threads[i])) {
err = PTR_ERR(threads[i]);
threads[i] = NULL;
goto kill_threads;
}
/* Place it onto correct cpu. */
kthread_bind(threads[i], i);
/* Make it highest prio. */
if (sched_setscheduler_nocheck(threads[i], SCHED_FIFO, &param))
BUG();
}
mutex_unlock(&stopmachine_mutex);
return p;
/* We've created all the threads. Wake them all: hold this CPU so one
* doesn't hit this CPU until we're ready. */
get_cpu();
for_each_online_cpu(i)
wake_up_process(threads[i]);
/* This will release the thread on our CPU. */
put_cpu();
wait_for_completion(&finished);
mutex_unlock(&lock);
kfree(threads);
return active.fnret;
kill_threads:
for_each_online_cpu(i)
if (threads[i])
kthread_stop(threads[i]);
mutex_unlock(&lock);
kfree(threads);
return err;
}
int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
int stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus)
{
struct task_struct *p;
int ret;
/* No CPUs can come up or down during this. */
get_online_cpus();
p = __stop_machine_run(fn, data, cpu);
if (!IS_ERR(p))
ret = kthread_stop(p);
else
ret = PTR_ERR(p);
ret = __stop_machine(fn, data, cpus);
put_online_cpus();
return ret;
}
EXPORT_SYMBOL_GPL(stop_machine_run);
EXPORT_SYMBOL_GPL(stop_machine);

6
kernel/trace/ftrace.c
View File

@ -587,7 +587,7 @@ static int __ftrace_modify_code(void *data)
static void ftrace_run_update_code(int command)
{
stop_machine_run(__ftrace_modify_code, &command, NR_CPUS);
stop_machine(__ftrace_modify_code, &command, NULL);
}
void ftrace_disable_daemon(void)
@ -787,7 +787,7 @@ static int ftrace_update_code(void)
!ftrace_enabled || !ftraced_trigger)
return 0;
stop_machine_run(__ftrace_update_code, NULL, NR_CPUS);
stop_machine(__ftrace_update_code, NULL, NULL);
return 1;
}
@ -1564,7 +1564,7 @@ static int __init ftrace_dynamic_init(void)
addr = (unsigned long)ftrace_record_ip;
stop_machine_run(ftrace_dyn_arch_init, &addr, NR_CPUS);
stop_machine(ftrace_dyn_arch_init, &addr, NULL);
/* ftrace_dyn_arch_init places the return code in addr */
if (addr) {

4
mm/page_alloc.c
View File

@ -2372,7 +2372,7 @@ static void build_zonelist_cache(pg_data_t *pgdat)
#endif /* CONFIG_NUMA */
/* return values int ....just for stop_machine_run() */
/* return values int ....just for stop_machine() */
static int __build_all_zonelists(void *dummy)
{
int nid;
@ -2397,7 +2397,7 @@ void build_all_zonelists(void)
} else {
/* we have to stop all cpus to guarantee there is no user
of zonelist */
stop_machine_run(__build_all_zonelists, NULL, NR_CPUS);
stop_machine(__build_all_zonelists, NULL, NULL);
/* cpuset refresh routine should be here */
}
vm_total_pages = nr_free_pagecache_pages();