[RFC PATCH 2/3] timer: del_timer_sync() can be used in softirq context

From: Yong Zhang
Date: Tue Aug 24 2010 - 03:00:33 EST


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: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---
kernel/timer.c | 8 +++-----
1 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/kernel/timer.c b/kernel/timer.c
index 55b6a2d..08c9559 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -981,7 +981,7 @@ 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.
@@ -991,12 +991,10 @@ 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 (;;) {
--
1.7.0.4

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