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.

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

Link: https://lore.kernel.org/lkml/20221123201306.823305113@linutronix.de/
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Pavel Machek <pavel@ucw.cz> [ LED ]
Acked-by: Kalle Valo <kvalo@kernel.org> [ wireless ]
Acked-by: Paolo Abeni <pabeni@redhat.com> [ networking ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/netfilter/xt_IDLETIMER.c b/net/netfilter/xt_IDLETIMER.c
index 0f8bb0bf558f..8d36303f3935 100644
--- a/net/netfilter/xt_IDLETIMER.c
+++ b/net/netfilter/xt_IDLETIMER.c
@@ -413,7 +413,7 @@ static void idletimer_tg_destroy(const struct xt_tgdtor_param *par)
 		pr_debug("deleting timer %s\n", info->label);
 
 		list_del(&info->timer->entry);
-		del_timer_sync(&info->timer->timer);
+		timer_shutdown_sync(&info->timer->timer);
 		cancel_work_sync(&info->timer->work);
 		sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);
 		kfree(info->timer->attr.attr.name);
@@ -441,7 +441,7 @@ static void idletimer_tg_destroy_v1(const struct xt_tgdtor_param *par)
 		if (info->timer->timer_type & XT_IDLETIMER_ALARM) {
 			alarm_cancel(&info->timer->alarm);
 		} else {
-			del_timer_sync(&info->timer->timer);
+			timer_shutdown_sync(&info->timer->timer);
 		}
 		cancel_work_sync(&info->timer->work);
 		sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);