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From e677edbcabee849bfdd43f1602bccbecf736a646 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Fri, 8 Apr 2022 11:08:58 -0600
Subject: [PATCH] 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>
---
fs/io_uring.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index fafd1ca4780b6..659f8ecba5b79 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -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);
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