[patch V2 08/17] timers: Use del_timer_sync() even on UP
From: Thomas Gleixner <hidden>
Date: 2022-11-22 17:45:51
Also in:
lkml, netdev
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 <redacted> Tested-by: Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/all/20220407161745.7d6754b3@gandalf.local.home (local) Link: https://lore.kernel.org/all/20221110064101.429013735@goodmis.org (local) --- include/linux/timer.h | 7 +------ kernel/time/timer.c | 2 -- 2 files changed, 1 insertion(+), 8 deletions(-)
--- a/include/linux/timer.h
+++ b/include/linux/timer.h@@ -183,12 +183,7 @@ extern int timer_reduce(struct timer_lis 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); extern void init_timers(void); struct hrtimer; --- a/kernel/time/timer.c +++ b/kernel/time/timer.c
@@ -1392,7 +1392,6 @@ static inline void timer_sync_wait_runni 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
@@ -1473,7 +1472,6 @@ int del_timer_sync(struct timer_list *ti return ret; } EXPORT_SYMBOL(del_timer_sync); -#endif static void call_timer_fn(struct timer_list *timer, void (*fn)(struct timer_list *),