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

From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Anna-Maria Behnsen <anna-maria@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Stephen Boyd <sboyd@kernel.org>,
	Guenter Roeck <linux@roeck-us.net>,
	Andrew Morton <akpm@linux-foundation.org>,
	Julia Lawall <Julia.Lawall@inria.fr>,
	Arnd Bergmann <arnd@arndb.de>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Marc Zyngier <maz@kernel.org>,
	Marcel Holtmann <marcel@holtmann.org>,
	Johan Hedberg <johan.hedberg@gmail.com>,
	Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
	linux-bluetooth@vger.kernel.org,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	netdev@vger.kernel.org
Subject: [patch V2 16/17] timers: Update the documentation to reflect on the new timer_shutdown() API
Date: Tue, 22 Nov 2022 18:45:10 +0100 (CET)	[thread overview]
Message-ID: <20221122173649.018971915@linutronix.de> (raw)
In-Reply-To: 20221122171312.191765396@linutronix.de

From: "Steven Rostedt (Google)" <rostedt@goodmis.org>

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>
Link: https://lore.kernel.org/r/20221110064147.712934793@goodmis.org
---
 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(-)

--- 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);

