From: Jens Axboe <[email protected]>
To: io-uring <[email protected]>
Cc: Dylan Yudaken <[email protected]>
Subject: [PATCH] io_uring: remove poll entry from list when canceling all
Date: Mon, 21 Mar 2022 19:14:12 -0600 [thread overview]
Message-ID: <[email protected]> (raw)
When the ring is exiting, as part of the shutdown, poll requests are
removed. But io_poll_remove_all() does not remove entries when finding
them, and since completions are done out-of-band, we can find and remove
the same entry multiple times.
We do guard the poll execution by poll ownership, but that does not
exclude us from reissuing a new one once the previous removal ownership
goes away.
This can race with poll execution as well, where we then end up seeing
req->apoll be NULL because a previous task_work requeue finished the
request.
Remove the poll entry when we find it and get ownership of it. This
prevents multiple invocations from finding it.
Fixes: aa43477b0402 ("io_uring: poll rework")
Reported-by: Dylan Yudaken <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
---
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 48f4540d7dd5..53bd71363a44 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6275,6 +6275,7 @@ static __cold bool io_poll_remove_all(struct io_ring_ctx *ctx,
list = &ctx->cancel_hash[i];
hlist_for_each_entry_safe(req, tmp, list, hash_node) {
if (io_match_task_safe(req, tsk, cancel_all)) {
+ hlist_del_init(&req->hash_node);
io_poll_cancel_req(req);
found = true;
}
--
Jens Axboe
reply other threads:[~2022-03-22 1:14 UTC|newest]
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