In order to avoid the false positive from lockdep, each per-cpu base->lock has
the separate lock class and migrate_hrtimers() uses double_spin_lock().
This is overcomplicated: except for migrate_hrtimers() we never take 2 locks at
once, and migrate_hrtimers() can use spin_lock_nested().
Signed-off-by: Oleg Nesterov <[EMAIL PROTECTED]>
--- 25/include/linux/hrtimer.h~3_HRTIMERS 2008-02-15 16:59:17.000000000
+0300
+++ 25/include/linux/hrtimer.h 2008-02-15 19:23:02.000000000 +0300
@@ -173,7 +173,6 @@ struct hrtimer_clock_base {
* struct hrtimer_cpu_base - the per cpu clock bases
* @lock: lock protecting the base and associated clock bases
* and timers
- * @lock_key: the lock_class_key for use with lockdep
* @clock_base: array of clock bases for this cpu
* @curr_timer: the timer which is executing a callback right
now
* @expires_next: absolute time of the next event which was scheduled
@@ -189,7 +188,6 @@ struct hrtimer_clock_base {
*/
struct hrtimer_cpu_base {
spinlock_t lock;
- struct lock_class_key lock_key;
struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
struct list_head cb_pending;
#ifdef CONFIG_HIGH_RES_TIMERS
--- 25/kernel/hrtimer.c~3_HRTIMERS 2008-02-15 16:59:17.000000000 +0300
+++ 25/kernel/hrtimer.c 2008-02-15 19:51:05.000000000 +0300
@@ -1411,7 +1411,6 @@ static void __cpuinit init_hrtimers_cpu(
int i;
spin_lock_init(&cpu_base->lock);
- lockdep_set_class(&cpu_base->lock, &cpu_base->lock_key);
for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++)
cpu_base->clock_base[i].cpu_base = cpu_base;
@@ -1452,16 +1451,16 @@ static void migrate_hrtimers(int cpu)
tick_cancel_sched_timer(cpu);
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);
for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
migrate_hrtimer_list(&old_base->clock_base[i],
&new_base->clock_base[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(hrtimer_bases);
}
--
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