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Thu, 13 Mar 2025 11:52:44 +0000 Received: from smtpav05.fra02v.mail.ibm.com (smtpav05.fra02v.mail.ibm.com [10.20.54.104]) by smtprelay05.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 52DBqgGh56885578 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 13 Mar 2025 11:52:42 GMT Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 363FA2005A; Thu, 13 Mar 2025 11:52:42 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D309720040; Thu, 13 Mar 2025 11:52:40 +0000 (GMT) Received: from li-c9696b4c-3419-11b2-a85c-f9edc3bf8a84.in.ibm.com (unknown [9.109.198.185]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 13 Mar 2025 11:52:40 +0000 (GMT) From: Nilay Shroff To: linux-block@vger.kernel.org Cc: hch@lst.de, ming.lei@redhat.com, dlemoal@kernel.org, hare@suse.de, axboe@kernel.dk, gjoyce@ibm.com Subject: [PATCHv2 3/3] block: protect debugfs attribute method hctx_busy_show Date: Thu, 13 Mar 2025 17:21:52 +0530 Message-ID: <20250313115235.3707600-4-nilay@linux.ibm.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250313115235.3707600-1-nilay@linux.ibm.com> References: <20250313115235.3707600-1-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: Y7FcOBJOJO8Dr7Nrp71Bz1e6jg8u8wlm X-Proofpoint-ORIG-GUID: Y7FcOBJOJO8Dr7Nrp71Bz1e6jg8u8wlm X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1093,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-03-13_05,2025-03-11_02,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 suspectscore=0 mlxlogscore=883 lowpriorityscore=0 spamscore=0 impostorscore=0 bulkscore=0 clxscore=1015 mlxscore=0 phishscore=0 adultscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502280000 definitions=main-2503130090 The hctx_busy_show method in debugfs is currently unprotected. This method iterates over all started requests in a tagset and prints them. However, the tags can be updated concurrently via the sysfs attributes 'nr_requests' or 'scheduler' (elevator switch), leading to potential race conditions. Since sysfs attributes 'nr_requests' and 'scheduler' are already protected using q->elevator_lock, extend this protection to the debugfs 'busy' attribute as well to ensure consistency. Signed-off-by: Nilay Shroff Reviewed-by: Christoph Hellwig --- block/blk-mq-debugfs.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c index 1c958bbaddce..3421b5521fe2 100644 --- a/block/blk-mq-debugfs.c +++ b/block/blk-mq-debugfs.c @@ -347,9 +347,14 @@ static int hctx_busy_show(void *data, struct seq_file *m) { struct blk_mq_hw_ctx *hctx = data; struct show_busy_params params = { .m = m, .hctx = hctx }; + int res; + res = mutex_lock_interruptible(&hctx->queue->elevator_lock); + if (res) + return res; blk_mq_tagset_busy_iter(hctx->queue->tag_set, hctx_show_busy_rq, ¶ms); + mutex_unlock(&hctx->queue->elevator_lock); return 0; }