From patchwork Sun Oct 8 09:48:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kemeng Shi X-Patchwork-Id: 13412520 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D720AE95A89 for ; Sun, 8 Oct 2023 01:48:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344303AbjJHBsQ (ORCPT ); Sat, 7 Oct 2023 21:48:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56582 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344267AbjJHBsP (ORCPT ); Sat, 7 Oct 2023 21:48:15 -0400 Received: from dggsgout12.his.huawei.com (unknown [45.249.212.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2AEF3B6; Sat, 7 Oct 2023 18:48:14 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.30.67.169]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4S34n20knsz4f3khf; Sun, 8 Oct 2023 09:48:06 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.124.27]) by APP1 (Coremail) with SMTP id cCh0CgBH0bFZCiJl7zQbCQ--.22902S3; Sun, 08 Oct 2023 09:48:11 +0800 (CST) From: Kemeng Shi To: viro@zeniv.linux.org.uk, brauner@kernel.org, dhowells@redhat.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/2] pipe: remove pipe_full check with wrong head in pipe_write Date: Sun, 8 Oct 2023 17:48:00 +0800 Message-Id: <20231008094801.354312-2-shikemeng@huaweicloud.com> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20231008094801.354312-1-shikemeng@huaweicloud.com> References: <20231008094801.354312-1-shikemeng@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: cCh0CgBH0bFZCiJl7zQbCQ--.22902S3 X-Coremail-Antispam: 1UD129KBjvdXoWruF13Cw1xAr45GF1xurWDXFb_yoWkKFgEka 97CFn3ur43Jr48Jw17CFnakryxW34Uur1UZrW5Ar9xJF1kWr98u3s5W34DC34UZ3Z8tF9x C392van2vr1fWjkaLaAFLSUrUUUUUb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUbf8YFVCjjxCrM7AC8VAFwI0_Gr0_Xr1l1xkIjI8I6I8E6xAIw20E Y4v20xvaj40_Wr0E3s1l1IIY67AEw4v_Jr0_Jr4l87I20VAvwVAaII0Ic2I_JFv_Gryl82 xGYIkIc2x26280x7IE14v26r18M28IrcIa0xkI8VCY1x0267AKxVWUXVWUCwA2ocxC64kI II0Yj41l84x0c7CEw4AK67xGY2AK021l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7 xvwVC0I7IYx2IY6xkF7I0E14v26r4UJVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2 z4x0Y4vEx4A2jsIEc7CjxVAFwI0_GcCE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4 xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v2 6r1j6r4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwCF04k20xvY0x0EwI xGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480 Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_JF0_Jw1lIxkGc2Ij64vIr41lIxAIcVC0I7 IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Jr0_Gr1lIxAIcVCF04k2 6cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxV AFwI0_Jr0_GrUvcSsGvfC2KfnxnUUI43ZEXa7IU0a0PDUUUUU== X-CM-SenderInfo: 5vklyvpphqwq5kxd4v5lfo033gof0z/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org In pipe_write we have: head = pipe->head; if (!pipe_full(head, pipe->tail, pipe->max_usage)) pipe->head = head + 1; /* write data to buffer at head */ /* supposed to check if pipe is full after write */ if (!pipe_full(head, pipe->tail, pipe->max_usage)) continue The second pipe_full expects head after write but head before write is used. Luckily, we will call pipe_full with correct reloaded pipe->head in new loop cycle and stop writing correctly. Remove wrong pipe_full check and simply continue to first pipe_full check after write done to avoid unnecessary check. Fixes: a194dfe6e6f6 ("pipe: Rearrange sequence in pipe_write() to preallocate slot") Signed-off-by: Kemeng Shi --- fs/pipe.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/fs/pipe.c b/fs/pipe.c index 2d88f73f585a..b19875720ff1 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -542,10 +542,9 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from) if (!iov_iter_count(from)) break; - } - if (!pipe_full(head, pipe->tail, pipe->max_usage)) continue; + } /* Wait for buffer space to become available. */ if ((filp->f_flags & O_NONBLOCK) || From patchwork Sun Oct 8 09:48:01 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kemeng Shi X-Patchwork-Id: 13412521 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7C451E95A8A for ; Sun, 8 Oct 2023 01:48:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344309AbjJHBsR (ORCPT ); Sat, 7 Oct 2023 21:48:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344279AbjJHBsP (ORCPT ); Sat, 7 Oct 2023 21:48:15 -0400 Received: from dggsgout11.his.huawei.com (unknown [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 01B3199; Sat, 7 Oct 2023 18:48:14 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.30.67.169]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4S34n60pFDz4f3jqt; Sun, 8 Oct 2023 09:48:10 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.124.27]) by APP1 (Coremail) with SMTP id cCh0CgBH0bFZCiJl7zQbCQ--.22902S4; Sun, 08 Oct 2023 09:48:11 +0800 (CST) From: Kemeng Shi To: viro@zeniv.linux.org.uk, brauner@kernel.org, dhowells@redhat.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] pipe: avoid repeat check of pipe->readers with pipe lock held Date: Sun, 8 Oct 2023 17:48:01 +0800 Message-Id: <20231008094801.354312-3-shikemeng@huaweicloud.com> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20231008094801.354312-1-shikemeng@huaweicloud.com> References: <20231008094801.354312-1-shikemeng@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: cCh0CgBH0bFZCiJl7zQbCQ--.22902S4 X-Coremail-Antispam: 1UD129KBjvdXoW7GFyDJF1xZrWxCw18WFyxuFg_yoWDtwbEk3 92yF1rWr1fJrWxXa17CF1ayr4UuryDAr17Zr1Yyr9rGF18WryDu3Z5ZFy8AryUXan8GF9x Ca9Fyr9rJr1xCjkaLaAFLSUrUUUUUb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUbfxYFVCjjxCrM7AC8VAFwI0_Xr0_Wr1l1xkIjI8I6I8E6xAIw20E Y4v20xvaj40_Wr0E3s1l1IIY67AEw4v_Jr0_Jr4l87I20VAvwVAaII0Ic2I_JFv_Gryl82 xGYIkIc2x26280x7IE14v26r15M28IrcIa0xkI8VCY1x0267AKxVWUCVW8JwA2ocxC64kI II0Yj41l84x0c7CEw4AK67xGY2AK021l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7 xvwVC0I7IYx2IY6xkF7I0E14v26r4UJVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2 z4x0Y4vEx4A2jsIEc7CjxVAFwI0_GcCE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4 xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v2 6r1j6r4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwCF04k20xvY0x0EwI xGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480 Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_JF0_Jw1lIxkGc2Ij64vIr41lIxAIcVC0I7 IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF04k2 6cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxV AFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x07jTQ6JUUUUU= X-CM-SenderInfo: 5vklyvpphqwq5kxd4v5lfo033gof0z/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Change to pipe->readers is protected by pipe_lock. Only recheck pipe->reader after relock to avoid repeat check of pipe->readers with pipe lock held. Signed-off-by: Kemeng Shi --- fs/pipe.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/fs/pipe.c b/fs/pipe.c index b19875720ff1..e9c63f66d1c7 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -479,13 +479,6 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from) } for (;;) { - if (!pipe->readers) { - send_sig(SIGPIPE, current, 0); - if (!ret) - ret = -EPIPE; - break; - } - head = pipe->head; if (!pipe_full(head, pipe->tail, pipe->max_usage)) { unsigned int mask = pipe->ring_size - 1; @@ -573,6 +566,12 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from) __pipe_lock(pipe); was_empty = pipe_empty(pipe->head, pipe->tail); wake_next_writer = true; + if (!pipe->readers) { + send_sig(SIGPIPE, current, 0); + if (!ret) + ret = -EPIPE; + break; + } } out: if (pipe_full(pipe->head, pipe->tail, pipe->max_usage))