diff mbox series

[V3,08/17] timers: Use del_timer_sync() even on UP

Message ID 20221123201624.888306160@linutronix.de
State New
Headers
Series timers: Provide timer_shutdown[_sync]() |

Commit Message

Thomas Gleixner Nov. 23, 2022, 8:18 p.m. UTC 
  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>
Link: https://lore.kernel.org/all/20220407161745.7d6754b3@gandalf.local.home
Link: https://lore.kernel.org/all/20221110064101.429013735@goodmis.org
---
 include/linux/timer.h |    7 +------
 kernel/time/timer.c   |    2 --
 2 files changed, 1 insertion(+), 8 deletions(-)
diff mbox series

Patch

--- 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
@@ -1396,7 +1396,6 @@  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
@@ -1477,7 +1476,6 @@  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 *),