From: Pavel Begunkov Date: Wed, 25 Aug 2021 19:51:39 +0000 (+0100) Subject: io_uring: clarify io_req_task_cancel() locking X-Git-Tag: microblaze-v5.16~84^2~24 X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=b18a1a4574d2d15f1b0c84658d4549ccbf241fee;p=linux-2.6-microblaze.git io_uring: clarify io_req_task_cancel() locking 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 Link: https://lore.kernel.org/r/71099083835f983a1fd73d5a3da6391924da8300.1629920396.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- diff --git a/fs/io_uring.c b/fs/io_uring.c index 5059049da242..09194f7276ba 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2168,7 +2168,7 @@ 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); } @@ -2177,7 +2177,6 @@ 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)))