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 45D77E77199 for ; Tue, 7 Jan 2025 06:31:41 +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=pMQiFqzMKsYUd5COwdvMVoaFbslLj2mcHOdXT5wS4Qc=; b=uY1haL7P/NCG5kcSx9QwkHX1aW zHiID4RVvW/60MVZQPuk/ddB4tWfY63VQJUi7+L93c3SKK8P8c+MN3rtUtbpKfQjOjTiUZtwr+IOg h7D0OQSIGL5nZl1KB+UIuVk08htfDJ1D/vS8eEnF+fpPDAZb0DnQJZ6ogBHej2AlfIjkX0yQfyQQo VYxBVUypsI1ozRZRumMghymz3uTg1rT1qJ27clB/3fQdHToG8uo4l+kzqbW00trwjiM0P6z+rcX5b jEtzFUlnVX4KKcJ/cR92wANQzzxjIWoq1IMoA7izYG48biVYHHWsuWfcRy3oHDby/TZ50W543W0ov 7bpczcqQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tV37r-00000003dz3-2weo; Tue, 07 Jan 2025 06:31:39 +0000 Received: from 2a02-8389-2341-5b80-d467-d75d-35bf-0eb6.cable.dynamic.v6.surfer.at ([2a02:8389:2341:5b80:d467:d75d:35bf:eb6] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tV37q-00000003dvo-0Nlj; Tue, 07 Jan 2025 06:31:38 +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 5/8] block: fix queue freeze vs limits lock order in sysfs store methods Date: Tue, 7 Jan 2025 07:30:37 +0100 Message-ID: <20250107063120.1011593-6-hch@lst.de> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20250107063120.1011593-1-hch@lst.de> References: <20250107063120.1011593-1-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 --- 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 8d69315e986d..3bac27fcd635 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -687,22 +687,24 @@ 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