[PATCH 1/2] io_uring: clarify io_req_task_cancel() locking
From: Pavel Begunkov <asml.silence@gmail.com>
Date: 2021-08-25 19:52:22
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
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