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 98C48C5ACD9 for ; Fri, 20 Feb 2026 16:31:35 +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:MIME-Version:References:Message-ID:Subject:Cc:To: From:Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=M8/OVHwRsfHW8M5wsM6NVhU4lqLzcoc5jo8xC3NZ8ZA=; b=tNtcBSpB9Bngn3w6bCC7IpOteo bxMwWY2acjUOleKgXevoheezA4JgZMF9jMa7oc50KqQ9pBlngrs+WIiWXA1vaIkBJ+0nyag4xX35L NFS2EBe8Fb1en51SqynAwmfOHPiPeDZeNWVVpMYT5Cz8P+45v+kOBTgKki/BOafxaFpypcZhjJ+P0 iioA86r5wPrs7XKOhP8jygUY50r/c4r3iL8tEgbprjthj9ibR4IqmewNutckDZxdkGpJxw+8zPUAz Bhonhf14gzf6jgQBakZbshpgbnBM2H/9RA3mRws8bghmuUHsQsDDhg7IwH04wIUMvcHVu6k1MEwNE NnLdWUrw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vtTPe-0000000FHQe-29t4; Fri, 20 Feb 2026 16:31:30 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vtTPb-0000000FHPb-2XMO for linux-nvme@lists.infradead.org; Fri, 20 Feb 2026 16:31:29 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1771605086; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=M8/OVHwRsfHW8M5wsM6NVhU4lqLzcoc5jo8xC3NZ8ZA=; b=JezuoQF4Fus0wBBvlw63k2ytE+x+OLApJ5zVhs5okSR3vfsEMkN6fZ33t0yKUQUaspI2Dx ftcj8B9H/dxGR+pktrsvPXOSSRFwVj4RsjLecwTorxJdQeqiec5BnPK4nQA786YcRb81nt jpJUsycEH/xOJSzUc0MzjvVJAzGUgt4= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-235-_cunhcL-P5ujd4hiEGDiRQ-1; Fri, 20 Feb 2026 11:31:22 -0500 X-MC-Unique: _cunhcL-P5ujd4hiEGDiRQ-1 X-Mimecast-MFC-AGG-ID: _cunhcL-P5ujd4hiEGDiRQ_1771605080 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D0489180049D; Fri, 20 Feb 2026 16:31:19 +0000 (UTC) Received: from fedora (unknown [10.72.116.11]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id F28E81800672; Fri, 20 Feb 2026 16:31:12 +0000 (UTC) Date: Sat, 21 Feb 2026 00:31:07 +0800 From: Ming Lei To: Caleb Sander Mateos Cc: Jens Axboe , Christoph Hellwig , Keith Busch , Sagi Grimberg , io-uring@vger.kernel.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, Anuj gupta , Kanchan Joshi Subject: Re: [PATCH v3 0/4] io_uring/uring_cmd: allow non-iopoll cmds with IORING_SETUP_IOPOLL Message-ID: References: <20260219172228.429479-1-csander@purestorage.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-Mimecast-MFC-PROC-ID: mzqvWTW5vfxQInqqF4C_dRu5FI2FA8YsHEOCO5c0uBs_1771605080 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260220_083127_737233_300CF6A3 X-CRM114-Status: GOOD ( 24.87 ) 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 Fri, Feb 20, 2026 at 08:22:29AM -0800, Caleb Sander Mateos wrote: > On Fri, Feb 20, 2026 at 8:11 AM Ming Lei wrote: > > > > On Fri, Feb 20, 2026 at 07:55:33AM -0800, Caleb Sander Mateos wrote: > > > On Fri, Feb 20, 2026 at 6:25 AM Ming Lei wrote: > > > > > > > > On Thu, Feb 19, 2026 at 10:22:23AM -0700, Caleb Sander Mateos wrote: > > > > > Currently, creating an io_uring with IORING_SETUP_IOPOLL requires all > > > > > requests issued to it to support iopoll. This prevents, for example, > > > > > using ublk zero-copy together with IORING_SETUP_IOPOLL, as ublk > > > > > zero-copy buffer registrations are performed using a uring_cmd. There's > > > > > no technical reason why these non-iopoll uring_cmds can't be supported. > > > > > They will either complete synchronously or via an external mechanism > > > > > that calls io_uring_cmd_done(), so they don't need to be polled. > > > > > > > > For sync uring command, it is fine to support for IOPOLL. > > > > > > > > However, there are async uring command, which may be completed in irq > > > > context, or in multishot way, at least the later isn't supported in > > > > io_do_iopoll() yet. > > > > > > Can you describe the issues you envision in more detail? > > > > Basically IOPOLL doesn't support multishot request yet. > > > > For example, when io_uring_mshot_cmd_post_cqe() is called and new cqe is > > queued, it can't be found from io_iopoll_check()<-io_uring_enter(IORING_ENTER_GETEVENTS). > > I don't think that's a new issue, though. You're right that > io_uring_mshot_cmd_post_cqe() assumes a non-REQ_F_IOPOLL request, so > it's up to the ->uring_cmd() implementation to ensure that (which ublk > already does). Since ublk's struct file_operations don't provide > ->uring_cmd_iopoll(), any ublk uring_cmds issued to an > IORING_SETUP_IOPOLL io_uring won't have REQ_F_IOPOLL set, so > io_uring_mshot_cmd_post_cqe() should work just fine. Please look in the following way: 1) without patch of `io_uring/uring_cmd: allow non-iopoll cmds with IORING_SETUP_IOPOLL`, multishot command submission can't succeed 2) with patch of "io_uring/uring_cmd: allow non-iopoll cmds with IORING_SETUP_IOPOLL", people may see hang forever in io_uring_enter() if multishot command is submitted in context IORING_SETUP_IOPOLL. Thanks, Ming