From: "Steven Rostedt (Google)" rostedt@goodmis.org
mainline inclusion from mainline-v6.2-rc1 commit a31323bef2b66455920d054b160c17d4240f8fd4 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7R8WG
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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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
Conflicts: Documentation/RCU/Design/Requirements/Requirements.rst Signed-off-by: Yu Liao liaoyu15@huawei.com --- 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(-)
diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst index ad2cc20131ec..e8af3dc3c95a 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 20710efa0322..a9cf9b233b77 100644 --- a/Documentation/kernel-hacking/locking.rst +++ b/Documentation/kernel-hacking/locking.rst @@ -1016,6 +1016,11 @@ 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������������������������������������������������ ``local.h`` ��������� ``asm-g
static void __exit test_exit(void) { - timer_delete_sync(&test_timer); + timer_shutdown_sync(&test_timer); }
module_init(test_init);