From 0d180406f2914aea3a78ddb880e2fe9ac78a9372 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 4 Apr 2008 20:54:10 +0200 Subject: [PATCH] timers: simplify lockdep handling In order to avoid the false positive from lockdep, each per-cpu base->lock has the separate lock class and migrate_timers() uses double_spin_lock(). This all is overcomplicated: except for migrate_timers() we never take 2 locks at once, and migrate_timers() can use spin_lock_nested(). Signed-off-by: Oleg Nesterov Cc: Arjan van de Ven Cc: Heiko Carstens Cc: Ingo Molnar Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner --- kernel/timer.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) diff --git a/kernel/timer.c b/kernel/timer.c index b024106daa7..f3d35d4ea42 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1228,13 +1228,6 @@ asmlinkage long sys_sysinfo(struct sysinfo __user *info) return 0; } -/* - * lockdep: we want to track each per-CPU base as a separate lock-class, - * but timer-bases are kmalloc()-ed, so we need to attach separate - * keys to them: - */ -static struct lock_class_key base_lock_keys[NR_CPUS]; - static int __cpuinit init_timers_cpu(int cpu) { int j; @@ -1277,7 +1270,6 @@ static int __cpuinit init_timers_cpu(int cpu) } spin_lock_init(&base->lock); - lockdep_set_class(&base->lock, base_lock_keys + cpu); for (j = 0; j < TVN_SIZE; j++) { INIT_LIST_HEAD(base->tv5.vec + j); @@ -1316,8 +1308,8 @@ static void __cpuinit migrate_timers(int cpu) new_base = get_cpu_var(tvec_bases); local_irq_disable(); - double_spin_lock(&new_base->lock, &old_base->lock, - smp_processor_id() < cpu); + spin_lock(&new_base->lock); + spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING); BUG_ON(old_base->running_timer); @@ -1330,8 +1322,8 @@ static void __cpuinit migrate_timers(int cpu) migrate_timer_list(new_base, old_base->tv5.vec + i); } - double_spin_unlock(&new_base->lock, &old_base->lock, - smp_processor_id() < cpu); + spin_unlock(&old_base->lock); + spin_unlock(&new_base->lock); local_irq_enable(); put_cpu_var(tvec_bases); }