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 9BED3E77197 for ; Mon, 6 Jan 2025 03:32:49 +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:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=wP7jolLUYxTGQVKFJKvtxIhzzFzEDzKghI1l/9u+ocU=; b=lhjc0RryqqRw94xxDWH5kMwVGe 2g/3nz+Y5p+ZnhUMiLE0e77kqZauNyONGSbackWBJNTlOPZcq/8s6UgFZhEm2IfFQBy8TdEfusIvd 3FEGDM5jRx+WMgaGs3InB1GsrQOBx/O232yb/Jd+FAXDKbKsbB46dx+xNtatsQ55juVITwmUQZl2J ighusD+D4NwqrOv/pYLS+y0dBmUyogird8onlGOaMP3CotonDums/mxZFT6VvY8V+XZ1OueE16x4V zZroVr4QHvWeqOu06yyvs4iiTKotc33I6fO7mbp5noZsr2yJKX4IwCedMXL9pDBtmAaQPO0A7Qct6 aXN15Cpw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tUdrB-000000008dM-3x9f; Mon, 06 Jan 2025 03:32:45 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tUdqV-000000008Wy-33Px for linux-nvme@lists.infradead.org; Mon, 06 Jan 2025 03:32:05 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1736134321; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=wP7jolLUYxTGQVKFJKvtxIhzzFzEDzKghI1l/9u+ocU=; b=Yny2wJA0kjCcRzTkshGKBUMO88+7z541wTSmbEqCOrquFsCPo/1h6lgrj1o+KPb6OY4Q6y BL7d37I5rm2DbR9U9Uo22eHmA79A5WwReuhfrNPShr1YN/RzeIjcMFRzVOg6iL7rqfmrBl EfpOnBhknHta2zJUa081Pz4DponIw18= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-671-KcX282JuPk29GhOFRtX-TA-1; Sun, 05 Jan 2025 22:31:57 -0500 X-MC-Unique: KcX282JuPk29GhOFRtX-TA-1 X-Mimecast-MFC-AGG-ID: KcX282JuPk29GhOFRtX-TA Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 002351956053; Mon, 6 Jan 2025 03:31:55 +0000 (UTC) Received: from fedora (unknown [10.72.116.65]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 630951956056; Mon, 6 Jan 2025 03:31:48 +0000 (UTC) Date: Mon, 6 Jan 2025 11:31:43 +0800 From: Ming Lei To: Damien Le Moal Cc: Jens Axboe , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, Christoph Hellwig , Keith Busch , Sagi Grimberg , Nilay Shroff Subject: Re: [PATCH 1/3] block: Fix sysfs queue freeze and limits lock order Message-ID: References: <20250104132522.247376-1-dlemoal@kernel.org> <20250104132522.247376-2-dlemoal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250104132522.247376-2-dlemoal@kernel.org> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250105_193203_841281_A5B17277 X-CRM114-Status: GOOD ( 23.95 ) 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 On Sat, Jan 04, 2025 at 10:25:20PM +0900, Damien Le Moal wrote: > 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 introducing the ->store_limit() operation in > struct queue_sysfs_entry and use this operation for all attributes that > modify the device queue limits through the QUEUE_RW_LIMIT_ENTRY() macro > definition. queue_attr_store() is modified to call the ->store_limit() > operation (if it is defined) without the device queue frozen. The device > queue freeze for attributes defining the ->stor_limit() operation is > moved to after the operation completes and is done only around the call > to queue_limits_commit_update(). > > Cc: stable@vger.kernel.org # v6.9+ > Signed-off-by: Damien Le Moal > --- > block/blk-sysfs.c | 123 ++++++++++++++++++++++++---------------------- > 1 file changed, 64 insertions(+), 59 deletions(-) > > diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c > index 767598e719ab..4fc0020c73a5 100644 > --- a/block/blk-sysfs.c > +++ b/block/blk-sysfs.c > @@ -24,6 +24,8 @@ struct queue_sysfs_entry { > struct attribute attr; > ssize_t (*show)(struct gendisk *disk, char *page); > ssize_t (*store)(struct gendisk *disk, const char *page, size_t count); > + ssize_t (*store_limit)(struct gendisk *disk, struct queue_limits *lim, > + const char *page, size_t count); As I mentioned in another thread, freezing queue may not be needed in ->store(), so let's discuss and confirm if it is needed here first. https://lore.kernel.org/linux-block/Z3tHozKiUqWr7gjO@fedora/ Also even though freeze is needed, I'd suggest to move freeze in each .store() callback for simplifying & avoiding regression. Thanks, Ming