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 ED4E620C034; Fri, 14 Feb 2025 07:42:01 +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=1739518922; cv=none; b=h/v3COqi7puoOgiu05GiE5tnIenaU34ZIDRJWES10oQOc2NNdd0m9gbVORgGrQHNBXyFZR4IRfYZIdL0W45suRGwjeZdR18aVu+W+EX5ZPg277OBHlkyZQqdTtWGz2DQKE8aRaKaaYt1LS6o2cCHHq8s2j7VKxUKZWpyIkHVbKo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739518922; c=relaxed/simple; bh=EDD9q/k0LYjcR7mWTHUsBXJQI1egklmZfCrvsVVR6wU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ffLff/+K0O6Z0wR12Ogc6/gW2EBmDpJekgHkDKXluI3jBVQAb9Nz1zX9KpIfP8noamLZyRykjjQQWfxKgFhfq0kFs7I6ELL067wZ3Q3gvBve6JSpJ1XgAt+0JSmKaxo8dG9aui/sLDU2zr5ZCUqh8W2c3z8s1LjafOmd6zlkBeA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xWPgsr/3; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="xWPgsr/3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ABBCEC4CED1; Fri, 14 Feb 2025 07:42:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1739518921; bh=EDD9q/k0LYjcR7mWTHUsBXJQI1egklmZfCrvsVVR6wU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=xWPgsr/3DGM34UvBmBtrGM/iTJ9rTlJxO/3yjH5IOnLTBJKIStDpcHvsoNMfHCjZn G5xzvDVYwN7RQezCc+HU/6A1qyYZThbJiVQUqa9HY/x7zBY67QjFYjRzprZ2c8X3pp rC8kXKRDwQRFFONN45gGLQ8BvPWfZig48aMJEQPc= Date: Fri, 14 Feb 2025 08:41:57 +0100 From: Greg Kroah-Hartman To: Naman Jain Cc: "K . Y . Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Stephen Hemminger , linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, stable@kernel.org, Saurabh Sengar Subject: Re: [RFC PATCH] uio_hv_generic: Fix sysfs creation path for ring buffer Message-ID: <2025021418-cork-rinse-698a@gregkh> References: <20250214064351.8994-1-namjain@linux.microsoft.com> <2025021455-tricky-rebalance-4acc@gregkh> Precedence: bulk X-Mailing-List: linux-hyperv@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 Fri, Feb 14, 2025 at 12:35:44PM +0530, Naman Jain wrote: > > > On 2/14/2025 12:21 PM, Greg Kroah-Hartman wrote: > > On Fri, Feb 14, 2025 at 12:13:51PM +0530, Naman Jain wrote: > > > On regular bootup, devices get registered to vmbus first, so when > > > uio_hv_generic driver for a particular device type is probed, > > > the device is already initialized and added, so sysfs creation in > > > uio_hv_generic probe works fine. However, when device is removed > > > and brought back, the channel rescinds and again gets registered > > > to vmbus. However this time, the uio_hv_generic driver is already > > > registered to probe for that device and in this case sysfs creation > > > is tried before the device gets initialized completely. Fix this by > > > deferring sysfs creation till device gets initialized completely. > > > > > > Problem path: > > > vmbus_device_register > > > device_register > > > uio_hv_generic probe > > > sysfs_create_bin_file (fails here) > > > > Ick, that's the issue, you shouldn't be manually creating sysfs files. > > Have the driver core do it for you at the proper time, which should make > > your logic much simpler, right? > > > > Set the default attribute groups instead of manually creating this and > > see if that works out better. > > > > thanks, > > > > greg k-h > > Thanks for reviewing Greg. I tried this approach and here are my > observations: > > What I could create with ATTRIBUTE_GROUPS: > /sys/bus/vmbus/devices/eb765408-105f-49b6-b4aa-c123b64d17d4/ring > > The one we have right now: > /sys/bus/vmbus/devices/eb765408-105f-49b6-b4aa-c123b64d17d4/channels/6/ring What is "channels" and "6" here? Are they real devices or just a directory name or something else? > I could not find a way to tweak attributes to create the "ring" under above > path. I could see the variations of sys_create_* which provides a > way to pass kobj and do that, but that is something we are already > using. No driver should EVER be pointing to a raw kobject, that's a huge hint that something is really wrong. Also, if a raw kobject is in a device path in the middle like this, it will not be seen properly from userspace library tools :( So again, what is creating the "channels" and "6" subdirectories? All of that shoudl be under full control by the uio device, right? thanks, greg k-h