From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5F32C33C9E for ; Sat, 11 Jan 2020 10:30:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A33DD20880 for ; Sat, 11 Jan 2020 10:30:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578738620; bh=CFNwPztFO66+fNuWLj9lWoBwPVGYz0e6dx8S1QsPuDk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=s9YTl21AFt0I63wNnF0ZXggYJ1CoeRak1IwQVt5msvEtHFks7UdNrU9vcQDgusr2k XmULa5on2w33KeUUh/BiFQFfXlpkzD9ourF07jI/WApTq1RlvuNttzv7VsWyScVgwz MOO66tWffVT5sD4/ny5hiUx0p3DXXxRo3UeZQEGc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731383AbgAKKaT (ORCPT ); Sat, 11 Jan 2020 05:30:19 -0500 Received: from mail.kernel.org ([198.145.29.99]:40460 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728889AbgAKKaR (ORCPT ); Sat, 11 Jan 2020 05:30:17 -0500 Received: from localhost (unknown [62.119.166.9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1D07C20842; Sat, 11 Jan 2020 10:30:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578738616; bh=CFNwPztFO66+fNuWLj9lWoBwPVGYz0e6dx8S1QsPuDk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2M1+ahFH/E2kDgquRRQbPCano75oRV9GIfN4/lg+2a78C71CnSVdMDVPoEvbt+4lE 9FTcNp5tSwDCgqw2oxX2BVHy7MlBW62jlHW4523txiPYhbwzXtS+JD7/TIPeThqbI9 bnkqKBmbLGNtatM48DnYibu4gcjJpu9HNG3f2/QI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pavel Begunkov , Jens Axboe , Sasha Levin Subject: [PATCH 5.4 108/165] io_uring: dont wait when under-submitting Date: Sat, 11 Jan 2020 10:50:27 +0100 Message-Id: <20200111094931.130840868@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200111094921.347491861@linuxfoundation.org> References: <20200111094921.347491861@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pavel Begunkov [ Upstream commit 7c504e65206a4379ff38fe41d21b32b6c2c3e53e ] There is no reliable way to submit and wait in a single syscall, as io_submit_sqes() may under-consume sqes (in case of an early error). Then it will wait for not-yet-submitted requests, deadlocking the user in most cases. Don't wait/poll if can't submit all sqes Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- fs/io_uring.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/io_uring.c b/fs/io_uring.c index a60c6315a348..709671faaed6 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -3721,6 +3721,9 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, mutex_lock(&ctx->uring_lock); submitted = io_ring_submit(ctx, to_submit); mutex_unlock(&ctx->uring_lock); + + if (submitted != to_submit) + goto out; } if (flags & IORING_ENTER_GETEVENTS) { unsigned nr_events = 0; @@ -3734,6 +3737,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, } } +out: percpu_ref_put(&ctx->refs); out_fput: fdput(f); -- 2.20.1