In order to make sure that a timer is not re-armed after it is stopped
before freeing, a new shutdown state is added to the timer code. The API
timer_shutdown_sync() and timer_shutdown() must be called before the
object that holds the timer can be freed.
Update the documentation to reflect this new workflow.
[ tglx: Updated to the new semantics and updated the zh_CN version ]
Signed-off-by: Steven Rostedt (Google) <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/r/20221110064147.712934793@goodmis.org
Link: https://lore.kernel.org/r/20221123201625.375284489@linutronix.de
one of its functions results in a segmentation fault. The module-unload
functions must therefore cancel any delayed calls to loadable-module
functions, for example, any outstanding mod_timer() must be dealt
one of its functions results in a segmentation fault. The module-unload
functions must therefore cancel any delayed calls to loadable-module
functions, for example, any outstanding mod_timer() must be dealt
-with via timer_delete_sync() or similar.
+with via timer_shutdown_sync() or similar.
Unfortunately, there is no way to cancel an RCU callback; once you
invoke call_rcu(), the callback function is eventually going to be
Unfortunately, there is no way to cancel an RCU callback; once you
invoke call_rcu(), the callback function is eventually going to be
static void __exit test_exit(void)
{
static void __exit test_exit(void)
{
- timer_delete_sync(&test_timer);
+ timer_shutdown_sync(&test_timer);
}
module_init(test_init);
}
module_init(test_init);
Because this is a fairly common case which is prone to races, you should
use timer_delete_sync() (``include/linux/timer.h``) to handle this case.
Because this is a fairly common case which is prone to races, you should
use timer_delete_sync() (``include/linux/timer.h``) to handle this case.
+Before freeing a timer, timer_shutdown() or timer_shutdown_sync() should be
+called which will keep it from being rearmed. Any subsequent attempt to
+rearm the timer will be silently ignored by the core code.
+
+
Locking Speed
=============
Locking Speed
=============
static void __exit test_exit(void)
{
static void __exit test_exit(void)
{
- timer_delete_sync(&test_timer);
+ timer_shutdown_sync(&test_timer);
}
module_init(test_init);
}
module_init(test_init);