4.19-stable review patch. If anyone has any objections, please let me know.
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From: Thomas Gleixner tglx@linutronix.de
[ 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@goodmis.org Signed-off-by: Steven Rostedt rostedt@goodmis.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Guenter Roeck linux@roeck-us.net Reviewed-by: Jacob Keller jacob.e.keller@intel.com Reviewed-by: Anna-Maria Behnsen anna-maria@linutronix.de Link: https://lore.kernel.org/all/20220407161745.7d6754b3@gandalf.local.home Link: https://lore.kernel.org/all/20221110064101.429013735@goodmis.org Link: https://lore.kernel.org/r/20221123201624.888306160@linutronix.de Stable-dep-of: 0f7352557a35 ("wifi: brcmfmac: Fix use-after-free bug in brcmf_cfg80211_detach") Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/timer.h | 7 +------ kernel/time/timer.c | 2 -- 2 files changed, 1 insertion(+), 8 deletions(-)
diff --git a/include/linux/timer.h b/include/linux/timer.h index 8e027cb10df01..a9c20a7ead305 100644 --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -171,12 +171,7 @@ 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 f63efe259ae46..489bb01796de4 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1349,7 +1349,6 @@ 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 @@ -1423,7 +1422,6 @@ 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 *),