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=-3.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH,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 04236C4321D for ; Thu, 16 Aug 2018 09:51:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9CBB1208A5 for ; Thu, 16 Aug 2018 09:51:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="AdIMSHsE" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9CBB1208A5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390653AbeHPMtD (ORCPT ); Thu, 16 Aug 2018 08:49:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:49774 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727206AbeHPMtC (ORCPT ); Thu, 16 Aug 2018 08:49:02 -0400 Received: from localhost.localdomain (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (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 680B6208A5; Thu, 16 Aug 2018 09:51:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1534413098; bh=OWsbrQ04NVLrFlxeygp3wC/xuQr/Njxo2Y40/YKeR3E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AdIMSHsE9xQpqqhZ9T13CJ9daDtuLuCFC4TpfGyxtdkhqJSjycEXSkwDhkg9nNNtO 6FoaTp6BFe+2koCnzEjMjr+sqhtcH83IVF2VcGs+bZFamcfNTLjUlA/o2BET7X1p0g 78dKyB+T6uc9s5SonANGEAcp4i+qjQq/apuJYWBo= From: Masami Hiramatsu To: Steven Rostedt Cc: Ingo Molnar , Masami Hiramatsu , linux-kernel@vger.kernel.org, Jens Axboe , linux-block@vger.kernel.org Subject: [PATCH 2/2] tracing/blktrace: Fix to allow setting same value Date: Thu, 16 Aug 2018 18:51:15 +0900 Message-Id: <153441307534.6024.2684721209411781531.stgit@devbox> X-Mailer: git-send-email 2.13.6 In-Reply-To: <153441301698.6024.1680500212551396320.stgit@devbox> References: <153441301698.6024.1680500212551396320.stgit@devbox> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Current trace-enable attribute in sysfs returns an error if user writes the same setting value as current one, e.g. # cat /sys/block/sda/trace/enable 0 # echo 0 > /sys/block/sda/trace/enable bash: echo: write error: Invalid argument # echo 1 > /sys/block/sda/trace/enable # echo 1 > /sys/block/sda/trace/enable bash: echo: write error: Device or resource busy But this is not a preferred behavior, it should ignore if new setting is same as current one. This fixes the problem as below. # cat /sys/block/sda/trace/enable 0 # echo 0 > /sys/block/sda/trace/enable # echo 1 > /sys/block/sda/trace/enable # echo 1 > /sys/block/sda/trace/enable Signed-off-by: Masami Hiramatsu Cc: Jens Axboe Cc: linux-block@vger.kernel.org --- kernel/trace/blktrace.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c index 987d9a9ae283..e67db1e8a000 100644 --- a/kernel/trace/blktrace.c +++ b/kernel/trace/blktrace.c @@ -1602,11 +1602,11 @@ static int blk_trace_remove_queue(struct request_queue *q) struct blk_trace *bt; bt = xchg(&q->blk_trace, NULL); - if (bt == NULL) - return -EINVAL; + if (bt != NULL) { + put_probe_ref(); + blk_trace_free(bt); + } - put_probe_ref(); - blk_trace_free(bt); return 0; } @@ -1619,6 +1619,9 @@ static int blk_trace_setup_queue(struct request_queue *q, struct blk_trace *bt = NULL; int ret = -ENOMEM; + if (q->blk_trace) + return 0; + bt = kzalloc(sizeof(*bt), GFP_KERNEL); if (!bt) return -ENOMEM;