tree cbed99bb8f0be689a864ae854bfab713e742d604
parent 7e9e9349d7f441761edde0c73718432b9a99b1a6
author Steven Rostedt (Google) <rostedt@goodmis.org> 1667769872 -0500
committer Steven Rostedt (Google) <rostedt@goodmis.org> 1667777270 -0500

treewide: Convert del_timer*() to timer_shutdown*()

Due to several bugs caused by timers being re-armed after they are
shutdown and just before they are freed, a new state of timers was added
called "shutdown". After a timer is set to this state, then it can no
longer be re-armed, and will trigger a warning if it is.

The following script was run to find all the trivial locations where
del_timer() or del_timer_sync() is called in the same function that the
object holding the timer is freed. It also ignores any locations where the
timer->function is modified between the del_timer*() and the free(), as
that is not considered a "trivial" case.

This was created by using a coccinelle script and the following commands:

 $ cat timer.cocci
@@
expression ptr, slab;
identifier timer, rfield;
@@
(
-       del_timer(&ptr->timer);
+       timer_shutdown(&ptr->timer);
|
-       del_timer_sync(&ptr->timer);
+       timer_shutdown_sync(&ptr->timer);
)
  ... when strict
      when != ptr->timer
(
        kfree_rcu(ptr, rfield);
|
        kmem_cache_free(slab, ptr);
|
        kfree(ptr);
)

 $ spatch --dir timer.cocci . > /tmp/t.patch
 $ patch -p1 < /tmp/t.patch

Link: https://lkml.kernel.org/r/20221106212702.547242324@goodmis.org

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Julia Lawall <Julia.Lawall@inria.fr>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>