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 DCAFED172AB for ; Mon, 2 Feb 2026 01:46:29 +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: Content-Type:In-Reply-To:From:References:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Cc:Content-ID:Content-Description:Resent-Date:Resent-From :Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=VBoUmLCN52TtNBbpEuxtWOTLGroUGAbnpWZuwFniV6s=; b=Zu5BQi2JiqBRXd0Nuauam6x5WN pjQZtYpIBPEWi3ddBi9PXcVaA+AsQxWWlUTs/i1NTOXekQ/PvdmwTBM2MTJ+zLhwFrQbe/QT4bp79 0mUexBhUEDaAmqQiD1dW5ET6RYTwuw6pkFK3h57O+hCDgNx+b/juCcGOPcD/HhEmsBfOeBIzNVsMv SFchbqic84UParjpyB/o0YzWW/tEra4rrcdTNGKKf/OV0uGhNh4AnHr8QEsLUWL2unNNxU8CbFx+T Rzp35eIzv+TQkiPJkTCmQI3qM+kUKpLD3jwGEnA+GM9mMhAWstIIM0bolMI2/Qt9Cxb+n0dOtSW3I NMsEsSbg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vmj1E-00000004JRq-2Ab9; Mon, 02 Feb 2026 01:46:24 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vmj1C-00000004JRR-0pbt for linux-nvme@lists.infradead.org; Mon, 02 Feb 2026 01:46:23 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 77F3640790; Mon, 2 Feb 2026 01:46:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C243CC4CEF7; Mon, 2 Feb 2026 01:46:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769996780; bh=mEtcjx/Rh9K5sMQHHB2eXHLBQKobn1llQUzLZc/8KzI=; h=Date:Subject:To:References:From:In-Reply-To:From; b=EBnwNml1FTyPW4lDYiuSrsPBx3e0caCyJcmPRXRw3IAl1BsxBvOsoXLZAP/U+rXQx WCAhNjjDnmtb24gjSFYpYZZRbVWteCXWNBQvc7p6YiQ2UYTPcP4oDahTvvbjnkDf5q 0CfsAyko5Aa+YiCCc7VtzRbrGA7SKYdJDs/JfDTYdp2gRImPHPbhr6A9PwO2bvRR1v V558wPm3Tfk2eXc5mXxwBxAtizAuas+pj2sG5bzp+G3n41wR4pOoAsny0d+Ueh48+Q d4Mr+gOkzcW3sBbYuSbU23VJU4wownDwGyVJv1tgm4KewqbBMYCRm2952H7wahelou +pr7Vb0iz7F4Q== Message-ID: <7ec5f552-197f-48be-9898-9cc4233783fc@kernel.org> Date: Mon, 2 Feb 2026 10:46:18 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [LSF/MM?BFP TOPIC] Block-layer device resets To: Hannes Reinecke , lsf-pc , "linux-block@vger.kernel.org" , "linux-nvme@lists.infradead.org" References: <50ee77fa-0c44-422e-9ee2-eece60b189e1@suse.de> Content-Language: en-US From: Damien Le Moal Organization: Western Digital Research In-Reply-To: <50ee77fa-0c44-422e-9ee2-eece60b189e1@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260201_174622_264219_5F2ABD3F X-CRM114-Status: GOOD ( 15.47 ) 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 2/2/26 02:06, Hannes Reinecke wrote: > Hi all, > > We are currently working on implementing cross-controller resets for > NVMe, which requires to send a command to the target which then should > terminate all commands on a given controller. > While we could easily terminate the controller, the specification > also requires us to terminate all outstanding commands. > Which then recurses into my all-time favourite topic on how to > abort outstanding commands from the fs/bio layer. > > However, here we don't have to dissect/match to individual commands, > but rather have to abort everything, which seems rather easier.s > > So I would like to fathom whether such a thing is feasible/reasonable > (I think so, obviously, and can think of several other use-cases, too, > qemu springs to mind here ...) and discuss possible implementations > (set 'req->deadline' to zero for all pending commands?). > Or maybe we can do such a thing already and I'm just not aware of it... Hmmm... Command timeouts ? E.g. if a controller is slow to respond (send completions), the block layer timeout timer may trigger, which will call into the low level device driver to force a reset. But before the reset actually happens, completions may actually come back, and we do handle that race correctly, well at least for scsi/ata. Your scenario sound very similar to this: once you reset the controller, whatever was pending will be silent and can be aborted or retried. So it does sound like that should not be too difficult, no ? Generalize the timeout processing or do something similar ? -- Damien Le Moal Western Digital Research