linux-kernel - [tip: timers/core] timers: Update the documentation to reflect on the new timer

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Message-ID: <166929936027.4906.15038032251708772543.tip-bot2@tip-bot2>
Date:   Thu, 24 Nov 2022 14:16:00 -0000
From:   "tip-bot2 for Steven Rostedt (Google)" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Steven Rostedt (Google)" <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Guenter Roeck <linux@...ck-us.net>,
        Jacob Keller <jacob.e.keller@...el.com>,
        "Anna-Maria Behnsen" <anna-maria@...utronix.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: timers/core] timers: Update the documentation to reflect on the
 new timer_shutdown() API

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     a31323bef2b66455920d054b160c17d4240f8fd4
Gitweb:        https://git.kernel.org/tip/a31323bef2b66455920d054b160c17d4240f8fd4
Author:        Steven Rostedt (Google) <rostedt@...dmis.org>
AuthorDate:    Wed, 23 Nov 2022 21:18:55 +01:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Thu, 24 Nov 2022 15:09:12 +01:00

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@...dmis.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Guenter Roeck <linux@...ck-us.net>
Reviewed-by: Jacob Keller <jacob.e.keller@...el.com>
Reviewed-by: Anna-Maria Behnsen <anna-maria@...utronix.de>
Link: https://lore.kernel.org/r/20221110064147.712934793@goodmis.org
Link: https://lore.kernel.org/r/20221123201625.375284489@linutronix.de

---
 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 546f23a..49387d8 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 a84f8b0..0b42cea 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 c5b8678..c756786 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 22493b9..eb5423f 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);