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Tue, 18 Feb 2025 08:29:20 +0000 Received: from smtpav04.fra02v.mail.ibm.com (smtpav04.fra02v.mail.ibm.com [10.20.54.103]) by smtprelay06.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 51I8TILI22937866 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 18 Feb 2025 08:29:19 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DA71D20043; Tue, 18 Feb 2025 08:29:18 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4BC1F20040; Tue, 18 Feb 2025 08:29:17 +0000 (GMT) Received: from li-c9696b4c-3419-11b2-a85c-f9edc3bf8a84.in.ibm.com (unknown [9.109.198.198]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 18 Feb 2025 08:29:17 +0000 (GMT) From: Nilay Shroff To: linux-block@vger.kernel.org Cc: hch@lst.de, ming.lei@redhat.com, dlemoal@kernel.org, axboe@kernel.dk, gjoyce@ibm.com Subject: [PATCHv2 4/6] blk-sysfs: protect nr_requests update using q->elevator_lock Date: Tue, 18 Feb 2025 13:58:57 +0530 Message-ID: <20250218082908.265283-5-nilay@linux.ibm.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250218082908.265283-1-nilay@linux.ibm.com> References: <20250218082908.265283-1-nilay@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: MXSz1MTvOth_f69PoBE85yJKxMs_WCOv X-Proofpoint-ORIG-GUID: MXSz1MTvOth_f69PoBE85yJKxMs_WCOv X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-02-18_03,2025-02-18_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 mlxlogscore=999 impostorscore=0 lowpriorityscore=0 malwarescore=0 phishscore=0 mlxscore=0 adultscore=0 suspectscore=0 bulkscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2501170000 definitions=main-2502180065 The sysfs attribute nr_requests could be simultaneously updated from elevator switch/update or nr_hw_queue update code path. The update to nr_requests for each of those code path now runs holding q->elevator_ lock. So we should now protect access to sysfs attribute nr_requests using q->elevator_lock instead of q->sysfs_lock. Signed-off-by: Nilay Shroff --- block/blk-sysfs.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 355dfb514712..37ac73468d4e 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -59,10 +59,11 @@ queue_var_store(unsigned long *var, const char *page, size_t count) static ssize_t queue_requests_show(struct gendisk *disk, char *page) { int ret; + struct request_queue *q = disk->queue; - mutex_lock(&disk->queue->sysfs_lock); - ret = queue_var_show(disk->queue->nr_requests, page); - mutex_unlock(&disk->queue->sysfs_lock); + mutex_lock(&q->elevator_lock); + ret = queue_var_show(q->nr_requests, page); + mutex_unlock(&q->elevator_lock); return ret; } @@ -75,8 +76,8 @@ queue_requests_store(struct gendisk *disk, const char *page, size_t count) unsigned int memflags; struct request_queue *q = disk->queue; - mutex_lock(&q->sysfs_lock); memflags = blk_mq_freeze_queue(q); + mutex_lock(&q->elevator_lock); if (!queue_is_mq(disk->queue)) { ret = -EINVAL; @@ -94,8 +95,9 @@ queue_requests_store(struct gendisk *disk, const char *page, size_t count) if (err) ret = err; out: + mutex_unlock(&q->elevator_lock); blk_mq_unfreeze_queue(q, memflags); - mutex_unlock(&q->sysfs_lock); + return ret; }