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=-9.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 EAB21C43603 for ; Sat, 14 Dec 2019 14:32:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C1BF824125 for ; Sat, 14 Dec 2019 14:32:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="QtDQUYh5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726701AbfLNOc1 (ORCPT ); Sat, 14 Dec 2019 09:32:27 -0500 Received: from mail-lj1-f193.google.com ([209.85.208.193]:38839 "EHLO mail-lj1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725872AbfLNOc0 (ORCPT ); Sat, 14 Dec 2019 09:32:26 -0500 Received: by mail-lj1-f193.google.com with SMTP id k8so1916641ljh.5; Sat, 14 Dec 2019 06:32:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:subject:date:message-id:in-reply-to:references:mime-version :content-transfer-encoding; bh=Eh8ihC6qfc/wJON6akO+nDoCfJM/SJL9lZfSseHNz9M=; b=QtDQUYh5xX4natfZkxU9TAw/+BANCFiRtYYhNQvA6WKmR12vI7iJWark1MmzbAXfHJ /wgeMkCUHku60elPojerq7WBLvoiCp30SMJYfRoOrRiGEuZBhwmwPb+CbXO0rxFNon3k rn8ZiTYjfFkVqq7lUQzLx3ess07wapMC3gbeX08VLYxa9askzmLSM8zVLNOU9NOy1/DN iMPZUyI89wEdllwaKj85UfsEquwiI+82BsVinT1WsDMG/4jzqzxFdUhuhbryaOYmuI1c nhXZxCuxySWigFeMbYrPJdrNb13EjFnz11y5MGorlLOqGb5ENuokNNhU7tX5DrZ5GqhW zKhg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=Eh8ihC6qfc/wJON6akO+nDoCfJM/SJL9lZfSseHNz9M=; b=YdP97L4tidmC2hbJ1xVPc+Ee5/wE1AWWv7T0iTOjSJc5FnHvxcEfij6MGlq3Anh4rX N0yelBJ7lK1ToJlKTXlm8hJR/bOeQvEInLVwe+6wQwO8tBdxsQou+oZX9KywmVAQMSZ/ HdASTnnKEQTmXjQiXf9qNrj+mMq52r895aq/ffC7TkDOcCk/k0sP6vcmXnGX58eICRNt hIdi9RjCfn4OfoC2E1kt1froKjTfCOm1fod2w+7wipaEDYcDOTbJNzZz/2UQwl1rKRLf fZj+CtKxakwJQBk0TN/y66Rly3uKtT/L/QufQXKDWc5gHNEKlRKSqoOTXBvp+1agKpBp pdHA== X-Gm-Message-State: APjAAAWpn8w94aS3RAt+f7JoE6QeGRwNdKOSre7/05EGMOHDgQq1VLya 5bGN4Unso1ESbWq/qk/bNXqm4A0WuvE= X-Google-Smtp-Source: APXvYqwkvAS1wgVDtwOqr56+ZWG1h7uv/J2tmU8uZ84jHXKNG1hXj9U8Py+/XDxHePhLgBrw3RXc0g== X-Received: by 2002:a2e:9705:: with SMTP id r5mr13321066lji.114.1576333944244; Sat, 14 Dec 2019 06:32:24 -0800 (PST) Received: from localhost.localdomain ([212.122.72.247]) by smtp.gmail.com with ESMTPSA id f11sm6873066lfa.9.2019.12.14.06.32.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 14 Dec 2019 06:32:23 -0800 (PST) From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] io_uring: don't wait when under-submitting Date: Sat, 14 Dec 2019 17:31:57 +0300 Message-Id: <6256169d519f72fe592e70be47a04aa0e9c3b9a1.1576333754.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: <5caa38be87f069eb4cc921d58ee1a98ff5d53978.1576223348.git.asml.silence@gmail.com> References: <5caa38be87f069eb4cc921d58ee1a98ff5d53978.1576223348.git.asml.silence@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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, and return -EAGAIN Signed-off-by: Pavel Begunkov --- v2: cap min_complete if submitted partially (Jens Axboe) fs/io_uring.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index c2f66e30a812..4c281f382bec 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -3526,11 +3526,8 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr, unsigned int sqe_flags; req = io_get_req(ctx, statep); - if (unlikely(!req)) { - if (!submitted) - submitted = -EAGAIN; + if (unlikely(!req)) break; - } if (!io_get_sqring(ctx, req)) { __io_free_req(req); break; @@ -4910,6 +4907,14 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, submitted = io_submit_sqes(ctx, to_submit, f.file, fd, &cur_mm, false); mutex_unlock(&ctx->uring_lock); + + if (submitted != to_submit) { + if (!submitted) { + submitted = -EAGAIN; + goto done; + } + min_complete = min(min_complete, (u32)submitted); + } } if (flags & IORING_ENTER_GETEVENTS) { unsigned nr_events = 0; @@ -4922,7 +4927,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, ret = io_cqring_wait(ctx, min_complete, sig, sigsz); } } - +done: percpu_ref_put(&ctx->refs); out_fput: fdput(f); -- 2.24.0