From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>, io-uring@vger.kernel.org
Subject: [PATCH 1/2] io_uring: clarify io_req_task_cancel() locking
Date: Wed, 25 Aug 2021 20:51:39 +0100 [thread overview]
Message-ID: <71099083835f983a1fd73d5a3da6391924da8300.1629920396.git.asml.silence@gmail.com> (raw)
In-Reply-To: <cover.1629920396.git.asml.silence@gmail.com>
It's too easy to forget and misjudge about synchronisation in
io_req_task_cancel(), add a comment clarifying it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 15728e63d6f9..712605fd04c2 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2138,7 +2138,7 @@ static void io_req_task_cancel(struct io_kiocb *req, bool *locked)
{
struct io_ring_ctx *ctx = req->ctx;
- /* ctx is guaranteed to stay alive while we hold uring_lock */
+ /* not needed for normal modes, but SQPOLL depends on it */
io_tw_lock(ctx, locked);
io_req_complete_failed(req, req->result);
}
@@ -2147,7 +2147,6 @@ static void io_req_task_submit(struct io_kiocb *req, bool *locked)
{
struct io_ring_ctx *ctx = req->ctx;
- /* ctx stays valid until unlock, even if we drop all ours ctx->refs */
io_tw_lock(ctx, locked);
/* req->task == current here, checking PF_EXITING is safe */
if (likely(!(req->task->flags & PF_EXITING)))
--
2.32.0
next prev parent reply other threads:[~2021-08-25 19:52 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-25 19:51 [PATCH for-next 0/2] 5.15 small improvements Pavel Begunkov
2021-08-25 19:51 ` Pavel Begunkov [this message]
2021-08-25 19:51 ` [PATCH 2/2] io_uring: add build check for buf_index overflows Pavel Begunkov
2021-08-27 15:23 ` [PATCH for-next 0/2] 5.15 small improvements Jens Axboe
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