From: Hao Xu <haoxu@linux.alibaba.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: io-uring@vger.kernel.org, Pavel Begunkov <asml.silence@gmail.com>,
Joseph Qi <joseph.qi@linux.alibaba.com>
Subject: [PATCH 1/3] io_uring: fix race between poll completion and cancel_hash insertion
Date: Wed, 22 Sep 2021 18:12:36 +0800 [thread overview]
Message-ID: <20210922101238.7177-2-haoxu@linux.alibaba.com> (raw)
In-Reply-To: <20210922101238.7177-1-haoxu@linux.alibaba.com>
If poll arming and poll completion runs parallelly, there maybe races.
For instance, run io_poll_add in iowq and io_poll_task_func in original
context, then:
iowq original context
io_poll_add
vfs_poll
(interruption happens
tw queued to original
context) io_poll_task_func
generate cqe
del from cancel_hash[]
if !poll.done
insert to cancel_hash[]
The entry left in cancel_hash[], similar case for fast poll.
Fix it by set poll.done = true when del from cancel_hash[].
Fixes: 5082620fb2ca ("io_uring: terminate multishot poll for CQ ring overflow")
Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
---
fs/io_uring.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 91e4c89abf78..4b0a40ad28b0 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5340,10 +5340,8 @@ static bool __io_poll_complete(struct io_kiocb *req, __poll_t mask)
}
if (req->poll.events & EPOLLONESHOT)
flags = 0;
- if (!io_cqring_fill_event(ctx, req->user_data, error, flags)) {
- req->poll.done = true;
+ if (!io_cqring_fill_event(ctx, req->user_data, error, flags))
flags = 0;
- }
if (flags & IORING_CQE_F_MORE)
ctx->cq_extra++;
@@ -5374,6 +5372,7 @@ static void io_poll_task_func(struct io_kiocb *req, bool *locked)
if (done) {
io_poll_remove_double(req);
hash_del(&req->hash_node);
+ req->poll.done = true;
} else {
req->result = 0;
add_wait_queue(req->poll.head, &req->poll.wait);
@@ -5511,6 +5510,7 @@ static void io_async_task_func(struct io_kiocb *req, bool *locked)
hash_del(&req->hash_node);
io_poll_remove_double(req);
+ apoll->poll.done = true;
spin_unlock(&ctx->completion_lock);
if (!READ_ONCE(apoll->poll.canceled))
--
2.24.4
next prev parent reply other threads:[~2021-09-22 10:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-22 10:12 [PATCH 0/3] poll fixes Hao Xu
2021-09-22 10:12 ` Hao Xu [this message]
2021-09-22 10:12 ` [PATCH 2/3] io_uring: fix lacking of EPOLLONESHOT Hao Xu
2021-09-22 10:12 ` [PATCH 3/3] io_uring: fix potential req refcount underflow Hao Xu
2021-09-22 15:55 ` [PATCH 0/3] poll fixes Jens Axboe
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