From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9E91836492A for ; Sun, 28 Jun 2026 14:20:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782656434; cv=none; b=XEDm+T4v92tp8r+bpwBcMhBBRAvVgemP9GMiiZbPf3mtCiUPFqmfC0MupPB6OaDCUMY45ojHj4Xy3RBRSX8Rx4lIfFXJRYVWWh3VBbLbviPS7H5yxkr9rg2wVTt0tqnw6jShdh151bhgOPWg5CQgMQCI3QP06ECvWCdJznolBeI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782656434; c=relaxed/simple; bh=DME1A9kYC0vpVXdpuDyjtBzaIRXFuwoE3ygSvRQy6Uk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ofocLKDh7Ioy6ZUDI3/qxoYTUbLboiB97UbtiIGB4b7Z9BaRkbdbhjbnB/aLYXpdjW6kxRkfeSaYGQME+HB+QKQastfN8drk/gg4SJ8CRvlT08TSSEyFFDX7vZvsoxcrRQ+lNPdR5A/k0t7aAWdg8whJpfKCAABGgdcr+YXR024= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OVjQcmUI; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="OVjQcmUI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3A80C1F00A3D; Sun, 28 Jun 2026 14:20:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782656433; bh=UWuiG7SWAs1hAxC9pRr9Q8Dn50ePtIzwA9LmhKHZhXA=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=OVjQcmUImehVDbp+1njEZLH3mvKTCtxnZt2dWSQ7ddQqzVsV6DUJ+03RQL6cVJJHT kmRx4JtJBo7kDLZR8aANb2GxkW6CfUI9OUIYT/qzhGNy8mFrxvxmeS62Ll4N6gzqzc MfimDkGXeTTIpzvDFMo6CbUESRaySP+zPtTeDvY3FdXd3Ol66rD8VLux5W8O/Pnynf WjWjmfa/8YxGyEZpS5eC5qpWTMqZeah/ynRpox2/8/s4g3gzG0bGMJ0Da8JVulDClI LqzYZGNArDuibv0Xh1ulYnqirJdp8QPge8xmMxssoql45w1iuqcEq4OIbsXKNI2NeS OuI4RmFACkJ8Q== Date: Sun, 28 Jun 2026 17:20:26 +0300 From: Leon Romanovsky To: Dennis Dalessandro Cc: Jiri Pirko , linux-rdma@vger.kernel.org, jgg@ziepe.ca, mrgolin@amazon.com Subject: Re: [PATCH rdma-next v2 4/6] RDMA/uverbs: Add ioctl method for CQ resize Message-ID: <20260628142026.GB33710@unreal> References: <20260615085040.1396623-1-jiri@resnulli.us> <20260615085040.1396623-5-jiri@resnulli.us> <20260617110605.GV327369@unreal> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Jun 18, 2026 at 11:40:29AM -0400, Dennis Dalessandro wrote: > On 6/17/26 7:06 AM, Leon Romanovsky wrote: > > On Mon, Jun 15, 2026 at 10:50:38AM +0200, Jiri Pirko wrote: > > > From: Jiri Pirko > > > > > > Resize CQ is currently only reachable through the legacy write() > > > uverbs command (IB_USER_VERBS_CMD_RESIZE_CQ). Add an equivalent modern > > > ioctl method, UVERBS_METHOD_CQ_RESIZE, on the CQ object so the > > > operation is available through the ioctl interface and can carry > > > per-attribute extensions. The handler mirrors the legacy command: it > > > looks up the CQ, calls resize_user_cq() and returns the new cqe count. > > > The legacy write path is left in place for ABI compatibility. > > > > I have a general question. Do we actually need CQ resizing, given that it is > > rarely implemented and often incorrect in existing drivers? Maybe this is a > > good time to consider deprecating that path. > > Can you expand on what you mean by incorrect in existing drivers? I mean I > see a glaring coding bug in our implementation but I can patch that. I had "create/resize CQ" series which fixed locking in all .resize_user_cq() implementations. The series stalled to give Jiri some space with his umem work. Part of that series can be found here: https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git/commit/?h=create-cq-entries-v1&id=c4f7b5999b4015609481657b437a92346a018d2c Thanks > > -Denny > >