[V2,16/17] timers: Update the documentation to reflect on the new timer_shutdown() API

Commit Message

Thomas Gleixner Nov. 22, 2022, 5:45 p.m. UTC

From: "Steven Rostedt (Google)" <[e-mail]>

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) <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Tested-by: Guenter Roeck <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
---
 Documentation/RCU/Design/Requirements/Requirements.rst  |    2 +-
 Documentation/core-api/local_ops.rst                    |    2 +-
 Documentation/kernel-hacking/locking.rst                |    5 +++++
 Documentation/translations/zh_CN/core-api/local_ops.rst |    2 +-
 4 files changed, 8 insertions(+), 3 deletions(-)

Patch

--- 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
 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
--- 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
 
     static void __exit test_exit(void)
     {
-            timer_delete_sync(&test_timer);
+            timer_shutdown_sync(&test_timer);
     }
 
     module_init(test_init);
--- a/Documentation/kernel-hacking/locking.rst
+++ b/Documentation/kernel-hacking/locking.rst
@@ -1007,6 +1007,11 @@  calling add_timer() at the end of their
 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
 =============
 
--- 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�
 
     static void __exit test_exit(void)
     {
-            timer_delete_sync(&test_timer);
+            timer_shutdown_sync(&test_timer);
     }
 
     module_init(test_init);