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, 2 insertions, 2 deletions

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 2f16e1bfb6e7..e43dfb9eb6ad 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -2184,7 +2184,7 @@ void drbd_destroy_device(struct kref *kref)
 	struct drbd_resource *resource = device->resource;
 	struct drbd_peer_device *peer_device, *tmp_peer_device;
 
-	del_timer_sync(&device->request_timer);
+	timer_shutdown_sync(&device->request_timer);
 
 	/* paranoia asserts */
 	D_ASSERT(device, device->open_cnt == 0);
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index df628e30bca4..1518a6423279 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1755,7 +1755,7 @@ static void lo_free_disk(struct gendisk *disk)
 	if (lo->workqueue)
 		destroy_workqueue(lo->workqueue);
 	loop_free_idle_workers(lo, true);
-	del_timer_sync(&lo->timer);
+	timer_shutdown_sync(&lo->timer);
 	mutex_destroy(&lo->lo_mutex);
 	kfree(lo);
 }