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 43578538A; Sun, 27 Oct 2024 20:30:59 +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=1730061061; cv=none; b=j0tko1hJPeYlmYhAhGSrwBC1KGr6A+KzDDf8DYZpbUMjMd5jCFHvu0kLLMfq6GKE4eM3zKfTfZj4KkCRKkmiw5bUsjwgWnWWMtYC7b4m23SmqyHWBWQiFXV1DdeFGBGaj+Ubu5C5cciFzPjKUt1nNHNOlWyW5hPS9moC3Zg7jao= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730061061; c=relaxed/simple; bh=g0qOuu9oBMe1flwJbOj0ETqlrVdC6doUvyj6Y4MWIJU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=KxR9T6Cf8NhMXSKTuByRYZOOTsn1KL8RtmT80REs88fBd8vAVByGtg5OlBD0jGimrgCdpw0aOmOt8FCDi44Bh4hweS1D1kW2FdJUzNW0Vjaa6StGv4MsRhNnaASnZZQE4ZVBa00f7e5jNxR2ooSBlVW/hvL4koAdtX36eSmAWHs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NmCZo5iF; 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="NmCZo5iF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4AA11C4CEC3; Sun, 27 Oct 2024 20:30:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730061059; bh=g0qOuu9oBMe1flwJbOj0ETqlrVdC6doUvyj6Y4MWIJU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=NmCZo5iFGA1y+uL3wW/0bcrnhx1UBxEVoEJpLLcF6HTtG2VUBSjSbG3NzcEqzMKA0 k8chJH5+oGGqHo+I7nZNxn1dud9nhRvQqo+jqsU/Zh4FxAWWbJfLc1wyTiuyaTNcVb PD+tXn3iIzdRyQJ/QmHMGIsShKIMA6k9wJatpXHVeBJmFjTpyk0VITjmsfp7GKuuED l9HaDBCa8SjI0qty5uX7/ykAVZA4JQDcUrWnO3E3jNE9/5FnP6R+kF7OTGkkaqkpwC i5j0wkoefJKYLi8ZrexHXbW5uGiKfILdA8ttSdF65bzOLVVc76CYIfx/gJiiP4kzWA 8Y7WOBQDlzHNw== Date: Sun, 27 Oct 2024 22:30:54 +0200 From: Leon Romanovsky To: Wenjia Zhang , Jakub Kicinski Cc: Wen Gu , "D. Wythe" , Tony Lu , David Miller , 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: <20241027203054.GB1615717@unreal> References: <20241025072356.56093-1-wenjia@linux.ibm.com> <20241027201857.GA1615717@unreal> 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: <20241027201857.GA1615717@unreal> On Sun, Oct 27, 2024 at 10:18:57PM +0200, 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") Honestly, this patch in Fixes line doesn't look right to me. It pokes inside of ib_device to get netdev index. For example call to smc_ib_ndev_change() will return completely unpredictable results, due to races. It is bad that RDMA ML wasn't even CCed back then, we would say NAK to this patch. https://lore.kernel.org/netdev/20201201192049.53517-6-kgraul@linux.ibm.com/ Thanks