From patchwork Tue Sep 24 07:52:23 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leonard Crestez X-Patchwork-Id: 11158225 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C066113B1 for ; Tue, 24 Sep 2019 08:03:39 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9E0E1207FD for ; Tue, 24 Sep 2019 08:03:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="mZYJMIBZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9E0E1207FD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nxp.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To: References:List-Owner; bh=WJLEtbEkdZ9+asYwxV3XBrFjSK3TfEs3n69diKeKxxk=; b=mZY JMIBZREQKmBvAwigisVR3k+gs8XvezEOAdTzc9H/uKVZLAJuRk/sivjkvW7/jRwluRWSulP1i6/NR sjx6wMHxsD/eIVeQF8LsYGkIMbmE0cFAL9CPaXq7ncSCM+N3Wv998HATRZ+IgM3M7UbhDIyEaBMzk OdPA/ulOuU3jNbsFB4R/cCaAcYbP345U6o7N8JHn4BgaV1E/E/1NVTapM7TT8CSXX8fvcSp4vV+RO Q5KhlOoxDiItqfxhs2wQwyAZsGzowZ2I9RsfoeK0mIuoLXMw22BadG3T88DuZMRYmFXjVWVarrP6N gXOcj8PiyVs38jLX+sx5ftUXFR+0xlw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.2 #3 (Red Hat Linux)) id 1iCfnP-0004Y2-4E; Tue, 24 Sep 2019 08:03:39 +0000 Received: from inva020.nxp.com ([92.121.34.13]) by bombadil.infradead.org with esmtps (Exim 4.92.2 #3 (Red Hat Linux)) id 1iCfce-0001bF-Rs for linux-arm-kernel@lists.infradead.org; Tue, 24 Sep 2019 07:52:35 +0000 Received: from inva020.nxp.com (localhost [127.0.0.1]) by inva020.eu-rdc02.nxp.com (Postfix) with ESMTP id 7A0B91A018B; Tue, 24 Sep 2019 09:52:31 +0200 (CEST) Received: from inva024.eu-rdc02.nxp.com (inva024.eu-rdc02.nxp.com [134.27.226.22]) by inva020.eu-rdc02.nxp.com (Postfix) with ESMTP id 6D02E1A0018; Tue, 24 Sep 2019 09:52:31 +0200 (CEST) Received: from fsr-ub1864-112.ea.freescale.net (fsr-ub1864-112.ea.freescale.net [10.171.82.98]) by inva024.eu-rdc02.nxp.com (Postfix) with ESMTP id F1E7B205E6; Tue, 24 Sep 2019 09:52:30 +0200 (CEST) From: Leonard Crestez To: MyungJoo Ham , Kyungmin Park , Chanwoo Choi , Matthias Kaehlcke Subject: [PATCH v3] PM / devfreq: Lock devfreq in trans_stat_show Date: Tue, 24 Sep 2019 10:52:23 +0300 Message-Id: X-Mailer: git-send-email 2.17.1 X-Virus-Scanned: ClamAV using ClamSMTP X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190924_005233_079744_0B9C25B1 X-CRM114-Status: GOOD ( 10.26 ) X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [92.121.34.13 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?utf-8?b?QXJ0dXIgxZp3aWdvxYQ=?= , linux-pm@vger.kernel.org, Krzysztof Kozlowski , Lukasz Luba , linux-imx@nxp.com, linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org There is no locking in this sysfs show function so stats printing can race with a devfreq_update_status called as part of freq switching or with initialization. Also add an assert in devfreq_update_status to make it clear that lock must be held by caller. Fixes: 39688ce6facd ("PM / devfreq: account suspend/resume for stats") Cc: stable@vger.kernel.org Signed-off-by: Leonard Crestez Reviewed-by: Matthias Kaehlcke Reviewed-by: Chanwoo Choi --- Changes since v2: * Move assert higher * Drop useless comment * Add Fixes: tag and Cc: stable Link to v2: https://patchwork.kernel.org/patch/11157315/ Changes since v1: * Split from series: low-priority bugfix not strictly required for PM QoS * Only keep lock during update, release before sprintf Link to v1: https://patchwork.kernel.org/patch/11149493/ drivers/devfreq/devfreq.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 072c0731659d..a2a045e117f0 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -158,10 +158,11 @@ static int set_freq_table(struct devfreq *devfreq) int devfreq_update_status(struct devfreq *devfreq, unsigned long freq) { int lev, prev_lev, ret = 0; unsigned long cur_time; + lockdep_assert_held(&devfreq->lock); cur_time = jiffies; /* Immediately exit if previous_freq is not initialized yet. */ if (!devfreq->previous_freq) goto out; @@ -1415,16 +1416,21 @@ static ssize_t trans_stat_show(struct device *dev, struct devfreq *devfreq = to_devfreq(dev); ssize_t len; int i, j; unsigned int max_state = devfreq->profile->max_state; - if (!devfreq->stop_polling && - devfreq_update_status(devfreq, devfreq->previous_freq)) - return 0; if (max_state == 0) return sprintf(buf, "Not Supported.\n"); + mutex_lock(&devfreq->lock); + if (!devfreq->stop_polling && + devfreq_update_status(devfreq, devfreq->previous_freq)) { + mutex_unlock(&devfreq->lock); + return 0; + } + mutex_unlock(&devfreq->lock); + len = sprintf(buf, " From : To\n"); len += sprintf(buf + len, " :"); for (i = 0; i < max_state; i++) len += sprintf(buf + len, "%10lu", devfreq->profile->freq_table[i]);