io_uring: fix race between timeout flush and removal

io_flush_timeouts() assumes the timeout isn't in progress of triggering
or being removed/canceled, so it unconditionally removes it from the
timeout list and attempts to cancel it.

Leave it on the list and let the normal timeout cancelation take care
of it.

Cc: stable@vger.kernel.org # 5.5+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2022-04-08 11:08:58 -06:00
parent 4cdd158be9
commit e677edbcab

View file

@ -1736,12 +1736,11 @@ static __cold void io_flush_timeouts(struct io_ring_ctx *ctx)
__must_hold(&ctx->completion_lock)
{
u32 seq = ctx->cached_cq_tail - atomic_read(&ctx->cq_timeouts);
struct io_kiocb *req, *tmp;
spin_lock_irq(&ctx->timeout_lock);
while (!list_empty(&ctx->timeout_list)) {
list_for_each_entry_safe(req, tmp, &ctx->timeout_list, timeout.list) {
u32 events_needed, events_got;
struct io_kiocb *req = list_first_entry(&ctx->timeout_list,
struct io_kiocb, timeout.list);
if (io_is_timeout_noseq(req))
break;
@ -1758,7 +1757,6 @@ static __cold void io_flush_timeouts(struct io_ring_ctx *ctx)
if (events_got < events_needed)
break;
list_del_init(&req->timeout.list);
io_kill_timeout(req, 0);
}
ctx->cq_last_tm_flush = seq;
@ -6628,6 +6626,7 @@ static int io_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe,
if (data->ts.tv_sec < 0 || data->ts.tv_nsec < 0)
return -EINVAL;
INIT_LIST_HEAD(&req->timeout.list);
data->mode = io_translate_timeout_mode(flags);
hrtimer_init(&data->timer, io_timeout_get_clock(data), data->mode);