The patch titled
timer: del_timer_sync() can be used in softirq context
has been added to the -mm tree. Its filename is
timer-del_timer_sync-can-be-used-in-softirq-context.patch
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------------------------------------------------------
Subject: timer: del_timer_sync() can be used in softirq context
From: Yong Zhang <yong.zhang@xxxxxxxxxxxxx>
Actually we have used del_timer_sync() in softirq context for a long time,
such as: __dst_free()::cancel_delayed_work() and maybe the
DEBUG_OBJECTS_TIMERS fundamental code.
So change the comments of it to warn on hardirq context only, and make
lockdep know about this change.
Signed-off-by: Yong Zhang <yong.zhang0@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/timer.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff -puN kernel/timer.c~timer-del_timer_sync-can-be-used-in-softirq-context kernel/timer.c
--- a/kernel/timer.c~timer-del_timer_sync-can-be-used-in-softirq-context
+++ a/kernel/timer.c
@@ -979,7 +979,7 @@ EXPORT_SYMBOL(try_to_del_timer_sync);
*
* Synchronization rules: Callers must prevent restarting of the timer,
* otherwise this function is meaningless. It must not be called from
- * interrupt contexts. The caller must not hold locks which would prevent
+ * hardirq contexts. The caller must not hold locks which would prevent
* completion of the timer's handler. The timer's handler must not call
* add_timer_on(). Upon exit the timer is not queued and the handler is
* not running on any CPU.
@@ -989,12 +989,10 @@ EXPORT_SYMBOL(try_to_del_timer_sync);
int del_timer_sync(struct timer_list *timer)
{
#ifdef CONFIG_LOCKDEP
- unsigned long flags;
-
- local_irq_save(flags);
+ local_bh_disable();
lock_map_acquire(&timer->lockdep_map);
lock_map_release(&timer->lockdep_map);
- local_irq_restore(flags);
+ local_bh_enable();
#endif
for (;;) {
_
Patches currently in -mm which might be from yong.zhang@xxxxxxxxxxxxx are
linux-next.patch
timer-make-try_to_del_timer_sync-safe-on-both-hardirq-context-and-up.patch
timer-del_timer_sync-can-be-used-in-softirq-context.patch
timer-warn-when-del_timer_sync-used-in-hardirq-context.patch
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