[tip: timers/cleanups] io_uring: Use helper function hrtimer_update_function()

[tip-bot2 for Nam Cao]

The following commit has been merged into the timers/cleanups branch of tip:

Commit-ID:     3f8d93d1371f460ed30ebfa30fb930c0605035fc
Gitweb:        https://git.kernel.org/tip/3f8d93d1371f460ed30ebfa30fb930c0605035fc
Author:        Nam Cao <namcao@xxxxxxxxxxxxx>
AuthorDate:    Wed, 05 Feb 2025 11:55:14 +01:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Tue, 18 Feb 2025 17:41:35 +01:00

io_uring: Use helper function hrtimer_update_function()

The field 'function' of struct hrtimer should not be changed directly, as
the write is lockless and a concurrent timer expiry might end up using the
wrong function pointer.

Switch to use hrtimer_update_function() which also performs runtime checks
that it is safe to modify the callback.

Signed-off-by: Nam Cao <namcao@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/all/9b33f490fb1d207d3918ef5e116dc3412ae35c1e.1738746927.git.namcao@xxxxxxxxxxxxx

---
 io_uring/io_uring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index ceacf62..936f8b4 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2421,7 +2421,7 @@ static enum hrtimer_restart io_cqring_min_timer_wakeup(struct hrtimer *timer)
 			goto out_wake;
 	}
 
-	iowq->t.function = io_cqring_timer_wakeup;
+	hrtimer_update_function(&iowq->t, io_cqring_timer_wakeup);
 	hrtimer_set_expires(timer, iowq->timeout);
 	return HRTIMER_RESTART;
 out_wake: