The patch titled
timer: make try_to_del_timer_sync() safe on both hardirq context and UP
has been added to the -mm tree. Its filename is
timer-make-try_to_del_timer_sync-safe-on-both-hardirq-context-and-up.patch
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------------------------------------------------------
Subject: timer: make try_to_del_timer_sync() safe on both hardirq context and UP
From: Yong Zhang <yong.zhang@xxxxxxxxxxxxx>
In commit fd450b7318b75343f ("timers: introduce try_to_del_timer_sync()")
, it was saying try_to_del_timer_sync() can be used in interrupt context.
But because base->running_timer is SMP special, this lead to unsymmetry
try_to_del_timer_sync() on UP and SMP.
We can make running_timer live on everywhere, then try_to_del_timer_sync()
is also UP safe and can be used in hardirq context.
Signed-off-by: Yong Zhang <yong.zhang0@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/timer.h | 4 ++--
kernel/timer.c | 6 +-----
2 files changed, 3 insertions(+), 7 deletions(-)
diff -puN include/linux/timer.h~timer-make-try_to_del_timer_sync-safe-on-both-hardirq-context-and-up include/linux/timer.h
--- a/include/linux/timer.h~timer-make-try_to_del_timer_sync-safe-on-both-hardirq-context-and-up
+++ a/include/linux/timer.h
@@ -249,11 +249,11 @@ static inline void timer_stats_timer_cle
extern void add_timer(struct timer_list *timer);
+extern int try_to_del_timer_sync(struct timer_list *timer);
+
#ifdef CONFIG_SMP
- extern int try_to_del_timer_sync(struct timer_list *timer);
extern int del_timer_sync(struct timer_list *timer);
#else
-# define try_to_del_timer_sync(t) del_timer(t)
# define del_timer_sync(t) del_timer(t)
#endif
diff -puN kernel/timer.c~timer-make-try_to_del_timer_sync-safe-on-both-hardirq-context-and-up kernel/timer.c
--- a/kernel/timer.c~timer-make-try_to_del_timer_sync-safe-on-both-hardirq-context-and-up
+++ a/kernel/timer.c
@@ -347,9 +347,7 @@ EXPORT_SYMBOL_GPL(set_timer_slack);
static inline void set_running_timer(struct tvec_base *base,
struct timer_list *timer)
{
-#ifdef CONFIG_SMP
base->running_timer = timer;
-#endif
}
static void internal_add_timer(struct tvec_base *base, struct timer_list *timer)
@@ -936,15 +934,12 @@ int del_timer(struct timer_list *timer)
}
EXPORT_SYMBOL(del_timer);
-#ifdef CONFIG_SMP
/**
* try_to_del_timer_sync - Try to deactivate a timer
* @timer: timer do del
*
* This function tries to deactivate a timer. Upon successful (ret >= 0)
* exit the timer is not queued and the handler is not running on any CPU.
- *
- * It must not be called from interrupt contexts.
*/
int try_to_del_timer_sync(struct timer_list *timer)
{
@@ -973,6 +968,7 @@ out:
}
EXPORT_SYMBOL(try_to_del_timer_sync);
+#ifdef CONFIG_SMP
/**
* del_timer_sync - deactivate a timer and wait for the handler to finish.
* @timer: the timer to be deactivated
_
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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