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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 61388E77188 for ; Wed, 8 Jan 2025 09:25:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=uJvbhGLt97FsIbhsJnskeRWyPNiZsDPKmhL4bk2h2rs=; b=Jje+N0qN9STMTCdB1NLXlt9mln keciaVj61Ehz1TBt68t8vDAhZnTjSmNh2FYSGfdn6whaaik/z56BGF0tUI3l0z4gwM4PuARlOf8A5 QlhIixnf6EF7lMWnICmZk4OJN4eQGVDf9nUf8QDWxbbe7OiD9kU+NnlOG6gp1wo79yWpX8pYE2+Vx cZiSQ6f9xP/j4ZPoFeYwnXkSfapvFxEGrkzSm/+mcKxxtkpZfS6ghZeuQdeujnMhH9esSsk6v76VE 3Tvmlw6lL4lE4g7WL4orsSUy2asXF1MsUsqmDsK3AeaYEBQ7iCGY4ldazC6G2dcRCRuTo0iEot8rd 3++pQCmQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tVSJq-00000007leY-3zxb; Wed, 08 Jan 2025 09:25:42 +0000 Received: from 2a02-8389-2341-5b80-e44b-b36a-6403-8f06.cable.dynamic.v6.surfer.at ([2a02:8389:2341:5b80:e44b:b36a:6403:8f06] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tVSJp-00000007lax-21ig; Wed, 08 Jan 2025 09:25:42 +0000 From: Christoph Hellwig To: Jens Axboe Cc: Damien Le Moal , Ming Lei , Nilay Shroff , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, nbd@other.debian.org, linux-scsi@vger.kernel.org, usb-storage@lists.one-eyed-alien.net Subject: [PATCH 05/10] block: fix queue freeze vs limits lock order in sysfs store methods Date: Wed, 8 Jan 2025 10:25:02 +0100 Message-ID: <20250108092520.1325324-6-hch@lst.de> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20250108092520.1325324-1-hch@lst.de> References: <20250108092520.1325324-1-hch@lst.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org queue_attr_store() always freezes a device queue before calling the attribute store operation. For attributes that control queue limits, the store operation will also lock the queue limits with a call to queue_limits_start_update(). However, some drivers (e.g. SCSI sd) may need to issue commands to a device to obtain limit values from the hardware with the queue limits locked. This creates a potential ABBA deadlock situation if a user attempts to modify a limit (thus freezing the device queue) while the device driver starts a revalidation of the device queue limits. Avoid such deadlock by not freezing the queue before calling the ->store_limit() method in struct queue_sysfs_entry and instead use the queue_limits_commit_update_frozen helper to freeze the queue after taking the limits lock. (commit log adapted from a similar patch from Damien Le Moal) Fixes: ff956a3be95b ("block: use queue_limits_commit_update in queue_discard_max_store") Fixes: 0327ca9d53bf ("block: use queue_limits_commit_update in queue_max_sectors_store") Signed-off-by: Christoph Hellwig Reviewed-by: Nilay Shroff --- block/blk-sysfs.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index f36356cbde0b..2de405cb5f10 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -691,22 +691,24 @@ queue_attr_store(struct kobject *kobj, struct attribute *attr, if (entry->load_module) entry->load_module(disk, page, length); - mutex_lock(&q->sysfs_lock); - blk_mq_freeze_queue(q); if (entry->store_limit) { struct queue_limits lim = queue_limits_start_update(q); res = entry->store_limit(disk, page, length, &lim); if (res < 0) { queue_limits_cancel_update(q); - } else { - res = queue_limits_commit_update(q, &lim); - if (!res) - res = length; + return res; } - } else { - res = entry->store(disk, page, length); + + res = queue_limits_commit_update_frozen(q, &lim); + if (res) + return res; + return length; } + + mutex_lock(&q->sysfs_lock); + blk_mq_freeze_queue(q); + res = entry->store(disk, page, length); blk_mq_unfreeze_queue(q); mutex_unlock(&q->sysfs_lock); return res; -- 2.45.2