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>

2 files changed, 4 insertions, 4 deletions

diff --git a/drivers/isdn/mISDN/l1oip_core.c b/drivers/isdn/mISDN/l1oip_core.c
index c24771336f61..f010b35a0531 100644
--- a/drivers/isdn/mISDN/l1oip_core.c
+++ b/drivers/isdn/mISDN/l1oip_core.c
@@ -1236,8 +1236,8 @@ release_card(struct l1oip *hc)
 
 	hc->shutdown = true;
 
-	del_timer_sync(&hc->keep_tl);
-	del_timer_sync(&hc->timeout_tl);
+	timer_shutdown_sync(&hc->keep_tl);
+	timer_shutdown_sync(&hc->timeout_tl);
 
 	cancel_work_sync(&hc->workq);
 
diff --git a/drivers/isdn/mISDN/timerdev.c b/drivers/isdn/mISDN/timerdev.c
index abdf36ac3bee..83d6b484d3c6 100644
--- a/drivers/isdn/mISDN/timerdev.c
+++ b/drivers/isdn/mISDN/timerdev.c
@@ -74,7 +74,7 @@ mISDN_close(struct inode *ino, struct file *filep)
 	while (!list_empty(list)) {
 		timer = list_first_entry(list, struct mISDNtimer, list);
 		spin_unlock_irq(&dev->lock);
-		del_timer_sync(&timer->tl);
+		timer_shutdown_sync(&timer->tl);
 		spin_lock_irq(&dev->lock);
 		/* it might have been moved to ->expired */
 		list_del(&timer->list);
@@ -204,7 +204,7 @@ misdn_del_timer(struct mISDNtimerdev *dev, int id)
 			list_del_init(&timer->list);
 			timer->id = -1;
 			spin_unlock_irq(&dev->lock);
-			del_timer_sync(&timer->tl);
+			timer_shutdown_sync(&timer->tl);
 			kfree(timer);
 			return id;
 		}