This is a note to let you know that I've just added the patch titled
timers: Use del_timer_sync() even on UP
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
timers-use-del_timer_sync-even-on-up.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3563faca31c6088cad3205a04c50be541bb30916
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Wed Nov 23 21:18:42 2022 +0100
timers: Use del_timer_sync() even on UP
[ Upstream commit 168f6b6ffbeec0b9333f3582e4cf637300858db5 ]
del_timer_sync() is assumed to be pointless on uniprocessor systems and can
be mapped to del_timer() because in theory del_timer() can never be invoked
while the timer callback function is executed.
This is not entirely true because del_timer() can be invoked from interrupt
context and therefore hit in the middle of a running timer callback.
Contrary to that del_timer_sync() is not allowed to be invoked from
interrupt context unless the affected timer is marked with TIMER_IRQSAFE.
del_timer_sync() has proper checks in place to detect such a situation.
Give up on the UP optimization and make del_timer_sync() unconditionally
available.
Co-developed-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Reviewed-by: Jacob Keller <jacob.e.keller@xxxxxxxxx>
Reviewed-by: Anna-Maria Behnsen <anna-maria@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/all/20220407161745.7d6754b3@xxxxxxxxxxxxxxxxxx
Link: https://lore.kernel.org/all/20221110064101.429013735@xxxxxxxxxxx
Link: https://lore.kernel.org/r/20221123201624.888306160@xxxxxxxxxxxxx
Stable-dep-of: 0f7352557a35 ("wifi: brcmfmac: Fix use-after-free bug in brcmf_cfg80211_detach")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/linux/timer.h b/include/linux/timer.h
index 1e6650ed066d5..4de865f516154 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -182,12 +182,7 @@ extern int timer_reduce(struct timer_list *timer, unsigned long expires);
extern void add_timer(struct timer_list *timer);
extern int try_to_del_timer_sync(struct timer_list *timer);
-
-#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)
- extern int del_timer_sync(struct timer_list *timer);
-#else
-# define del_timer_sync(t) del_timer(t)
-#endif
+extern int del_timer_sync(struct timer_list *timer);
#define del_singleshot_timer_sync(t) del_timer_sync(t)
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 973c66d9b3f90..0dfd1cacc4a00 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1345,7 +1345,6 @@ static inline void timer_sync_wait_running(struct timer_base *base) { }
static inline void del_timer_wait_running(struct timer_list *timer) { }
#endif
-#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)
/**
* del_timer_sync - Deactivate a timer and wait for the handler to finish.
* @timer: The timer to be deactivated
@@ -1419,7 +1418,6 @@ int del_timer_sync(struct timer_list *timer)
return ret;
}
EXPORT_SYMBOL(del_timer_sync);
-#endif
static void call_timer_fn(struct timer_list *timer,
void (*fn)(struct timer_list *),
