From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 8E8031C231D; Tue, 5 Nov 2024 11:23:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730805800; cv=none; b=lqUVei4tEPoD1z36CZglAebRUBTeByvCbbofY4pWuqj5imV0t8UjebdRAQibLjvInUTuU+Fzv/p+3VYH5E0xI/zFXa87vrOCDho2OZJDG70vS464ViABAWjELb4QoF4ps52Y4qp/l/fv/VO1iA6muYNpApEfmhq4SYCZvWP5B8Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730805800; c=relaxed/simple; bh=Q4eFHakxqG1dy0iztrcXVHW6AoWr7/YCu3Tso2wXTes=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=SksMdnbddaq0QaW5FLPX2CVhVRFMoXN6IxxZRGOH467SXNxQZJceQ1S0G10c+cIdlssUC3/+wT/2DGSBMysIVBX4v6LUvSclGo3+dPh4EfOEmPmU9ONWMwoVOx3PEb9qVpdcLleRTJZ5JjNJwL+AbooVWgiR2fmOfUyNAnOXY0A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LvSqOd+F; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LvSqOd+F" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 37746C4CECF; Tue, 5 Nov 2024 11:23:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730805799; bh=Q4eFHakxqG1dy0iztrcXVHW6AoWr7/YCu3Tso2wXTes=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LvSqOd+FpiQYVvwsnR9O/gyWLdcHj2QAEsch1GsCYnZEKsLfggk7QMRwPMWpqLXzb byx45L3BnNdxMjSd7VqPXJGMCGqbWkpdOuRnMplz9NK1Hj+gU7ttzixvdXnt6C2OPi HL5o47VMSW7FJ5uq0/jE/1inQFqTe0tPagqtRjYjJ0gUL6Z6ViA2PceFEsCgV6pS7Z ZAuEac/TpBfolAonnqg4Me+1LKmLQaH4D8nInbN09OdEEBEtebhJVvlpZTBSg6QeOE HShknlEUbyHR3o5w1TEePyclgcQcBMhOWZWVyY2Co7I0+u0j47D2Ez+1guGHSxrJvh xSAsuPuWQ4mSQ== Date: Tue, 5 Nov 2024 13:23:13 +0200 From: Leon Romanovsky To: Wenjia Zhang Cc: Wen Gu , "D. Wythe" , Tony Lu , David Miller , Jakub Kicinski , Eric Dumazet , Paolo Abeni , netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org, Heiko Carstens , Jan Karcher , Gerd Bayer , Alexandra Winter , Halil Pasic , Nils Hoppmann , Niklas Schnell , Thorsten Winkler , Karsten Graul , Stefan Raspl , Aswin K Subject: Re: [PATCH net] net/smc: Fix lookup of netdev by using ib_device_get_netdev() Message-ID: <20241105112313.GE311159@unreal> References: <20241025072356.56093-1-wenjia@linux.ibm.com> <20241027201857.GA1615717@unreal> <8d17b403-aefa-4f36-a913-7ace41cf2551@linux.ibm.com> Precedence: bulk X-Mailing-List: netdev@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: <8d17b403-aefa-4f36-a913-7ace41cf2551@linux.ibm.com> On Tue, Nov 05, 2024 at 10:50:45AM +0100, Wenjia Zhang wrote: > > > On 27.10.24 21:18, Leon Romanovsky wrote: > > On Fri, Oct 25, 2024 at 09:23:55AM +0200, Wenjia Zhang wrote: > > > Commit c2261dd76b54 ("RDMA/device: Add ib_device_set_netdev() as an > > > alternative to get_netdev") introduced an API ib_device_get_netdev. > > > The SMC-R variant of the SMC protocol continued to use the old API > > > ib_device_ops.get_netdev() to lookup netdev. > > > > I would say that calls to ibdev ops from ULPs was never been right > > thing to do. The ib_device_set_netdev() was introduced for the drivers. > > > > So the whole commit message is not accurate and better to be rewritten. > > > > > As this commit 8d159eb2117b > > > ("RDMA/mlx5: Use IB set_netdev and get_netdev functions") removed the > > > get_netdev callback from mlx5_ib_dev_common_roce_ops, calling > > > ib_device_ops.get_netdev didn't work any more at least by using a mlx5 > > > device driver. > > > > It is not a correct statement too. All modern drivers (for last 5 years) > > don't have that .get_netdev() ops, so it is not mlx5 specific, but another > > justification to say that SMC-R was doing it wrong. > > > > > Thus, using ib_device_set_netdev() now became mandatory. > > > > ib_device_set_netdev() is mandatory for the drivers, it is nothing to do > > with ULPs. > > > > > > > > Replace ib_device_ops.get_netdev() with ib_device_get_netdev(). > > > > It is too late for me to do proper review for today, but I would say > > that it is worth to pay attention to multiple dev_put() calls in the > > functions around the ib_device_get_netdev(). > > > > > > > > Fixes: 54903572c23c ("net/smc: allow pnetid-less configuration") > > > Fixes: 8d159eb2117b ("RDMA/mlx5: Use IB set_netdev and get_netdev functions") > > > > It is not related to this change Fixes line. > > > > Hi Leon, > > Thank you for the review! I agree that SMC could do better. However, we > should fix it and give enough information and reference on the changes, > since the code has already existed and didn't work with the old way. The code which you change worked by chance and was wrong from day one. > I can rewrite the commit message. > > What about: > " > The SMC-R variant of the SMC protocol still called > ib_device_ops.get_netdev() to lookup netdev. As we used mlx5 device driver > to run SMC-R, it failed to find a device, because in mlx5_ib the internal > net device management for retrieving net devices was replaced by a common > interface ib_device_get_netdev() in commit 8d159eb2117b ("RDMA/mlx5: Use IB > set_netdev and get_netdev functions"). Thus, replace > ib_device_ops.get_netdev() with ib_device_get_netdev() in SMC. > " The SMC-R variant of the SMC protocol used direct call to ib_device_ops.get_netdev() function to lookup netdev. Such direct accesses are not correct for any usage outside of RDMA core code. RDMA subsystem provides ib_device_get_netdev() function that works on all RDMA drivers returns valid netdev with proper locking an reference counting. The commit 8d159eb2117b ("RDMA/mlx5: Use IB set_netdev and get_netdev functions") exposed that SMC-R didn't use that function. So update the SMC-R to use proper API, Thanks