From patchwork Fri Mar 19 12:19:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "gregkh@linuxfoundation.org" X-Patchwork-Id: 405393 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham 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 99ABBC43332 for ; Fri, 19 Mar 2021 12:21:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 784C464F8B for ; Fri, 19 Mar 2021 12:21:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231209AbhCSMVS (ORCPT ); Fri, 19 Mar 2021 08:21:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:59498 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231393AbhCSMVH (ORCPT ); Fri, 19 Mar 2021 08:21:07 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 235396146D; Fri, 19 Mar 2021 12:20:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1616156458; bh=ckCEMwkTdHRUK+3A65B6sHIP4/kzvgiVMTUppH3d7tE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=C0KeuyBasyPAPk6KdzZ0lg+KdxL4gAFLR7jkVpjWBHJ+80mOZmYS8zmfMAjEFd7tI D0opEaWe0zQIh6WAVS6P6jni+WQXPP+aHDrcXSJOdh59dq25dk1ODB/SJwqhrznTPj KgC1+rtdZR57ieKqIYnIepz93ZYyWtEkfP/KPL1A= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jens Axboe , Sasha Levin Subject: [PATCH 5.11 09/31] io_uring: dont keep looping for more events if we cant flush overflow Date: Fri, 19 Mar 2021 13:19:03 +0100 Message-Id: <20210319121747.504718297@linuxfoundation.org> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20210319121747.203523570@linuxfoundation.org> References: <20210319121747.203523570@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Jens Axboe [ Upstream commit ca0a26511c679a797f86589894a4523db36d833e ] It doesn't make sense to wait for more events to come in, if we can't even flush the overflow we already have to the ring. Return -EBUSY for that condition, just like we do for attempts to submit with overflow pending. Cc: stable@vger.kernel.org # 5.11 Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- fs/io_uring.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 7621978e9fc8..cab380a337e4 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1823,18 +1823,22 @@ static bool __io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force, return all_flushed; } -static void io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force, +static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force, struct task_struct *tsk, struct files_struct *files) { + bool ret = true; + if (test_bit(0, &ctx->cq_check_overflow)) { /* iopoll syncs against uring_lock, not completion_lock */ if (ctx->flags & IORING_SETUP_IOPOLL) mutex_lock(&ctx->uring_lock); - __io_cqring_overflow_flush(ctx, force, tsk, files); + ret = __io_cqring_overflow_flush(ctx, force, tsk, files); if (ctx->flags & IORING_SETUP_IOPOLL) mutex_unlock(&ctx->uring_lock); } + + return ret; } static void __io_cqring_fill_event(struct io_kiocb *req, long res, long cflags) @@ -7280,11 +7284,16 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, iowq.nr_timeouts = atomic_read(&ctx->cq_timeouts); trace_io_uring_cqring_wait(ctx, min_events); do { - io_cqring_overflow_flush(ctx, false, NULL, NULL); + /* if we can't even flush overflow, don't wait for more */ + if (!io_cqring_overflow_flush(ctx, false, NULL, NULL)) { + ret = -EBUSY; + break; + } prepare_to_wait_exclusive(&ctx->wait, &iowq.wq, TASK_INTERRUPTIBLE); ret = io_cqring_wait_schedule(ctx, &iowq, &timeout); finish_wait(&ctx->wait, &iowq.wq); + cond_resched(); } while (ret > 0); restore_saved_sigmask_unless(ret == -EINTR);