diff options
| author | Steven Rostedt (Google) <rostedt@goodmis.org> | 2022-11-23 21:18:55 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2022-11-24 15:09:12 +0100 |
| commit | a31323bef2b66455920d054b160c17d4240f8fd4 (patch) | |
| tree | b7c9ba77bc3b47b7333e2024a3668bcd30c763e9 | |
| parent | f571faf6e443b6011ccb585d57866177af1f643c (diff) | |
timers: Update the documentation to reflect on the new timer_shutdown() API
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
| -rw-r--r-- | Documentation/RCU/Design/Requirements/Requirements.rst | 2 | ||||
| -rw-r--r-- | Documentation/core-api/local_ops.rst | 2 | ||||
| -rw-r--r-- | Documentation/kernel-hacking/locking.rst | 5 | ||||
| -rw-r--r-- | Documentation/translations/zh_CN/core-api/local_ops.rst | 2 |
4 files changed, 8 insertions, 3 deletions
diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst index 546f23abeca3..49387d823619 100644 --- a/Documentation/RCU/Design/Requirements/Requirements.rst +++ b/Documentation/RCU/Design/Requirements/Requirements.rst @@ -1858,7 +1858,7 @@ unloaded. After a given module has been unloaded, any attempt to call 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 diff --git a/Documentation/core-api/local_ops.rst b/Documentation/core-api/local_ops.rst index a84f8b0c7ab2..0b42ceaaf3c4 100644 --- a/Documentation/core-api/local_ops.rst +++ b/Documentation/core-api/local_ops.rst @@ -191,7 +191,7 @@ Here is a sample module which implements a basic per cpu counter using static void __exit test_exit(void) { - timer_delete_sync(&test_timer); + timer_shutdown_sync(&test_timer); } module_init(test_init); diff --git a/Documentation/kernel-hacking/locking.rst b/Documentation/kernel-hacking/locking.rst index c5b8678ed232..c756786e17ae 100644 --- a/Documentation/kernel-hacking/locking.rst +++ b/Documentation/kernel-hacking/locking.rst @@ -1007,6 +1007,11 @@ calling add_timer() at the end of their timer function). 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 ============= diff --git a/Documentation/translations/zh_CN/core-api/local_ops.rst b/Documentation/translations/zh_CN/core-api/local_ops.rst index 22493b9b829c..eb5423f60f17 100644 --- a/Documentation/translations/zh_CN/core-api/local_ops.rst +++ b/Documentation/translations/zh_CN/core-api/local_ops.rst @@ -185,7 +185,7 @@ UP之间没有不同的行为，在你的架构的 ``local.h`` 中包括 ``asm-g static void __exit test_exit(void) { - timer_delete_sync(&test_timer); + timer_shutdown_sync(&test_timer); } module_init(test_init); |