From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 57D6754774; Mon, 4 Aug 2025 05:49:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754286586; cv=none; b=GELxKhC+EUuJqYZ/UDCHv+IXPwmH+hD1mkKO4oFR0UbA+3gurHMGTCeFi3AqKyA5dMQGrj/XoZTYbFT+r/d2GRJwjgS6y0lrA1QNXjO0oovm3CfdtjoJXGW5FPTZLD6NxQqwZ+o8gffoio4kIVPd1Q/HL6hTeteaUfrei6aDSkk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754286586; c=relaxed/simple; bh=N0ifEoKADJ266dZ1TZEK7VwvwBuXGKpaWyjwuR91ViU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eAZpFFt6R1Gqz8SKI9yUkuyAkkZY5k7XxOWEoCn/ue4qL7yzjuXxpA+u7QsHpZqEtIXP5hN03NvjQmMP9nN2uXgN82PFtnOgEJQ8j8a3C3OGf9GYYWLRhVL3LmJDyv7pWbttV5zFxAXXU3+v7V9BkwTRVwwRHCxZCm77s1NkLBE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=qmmHUbDG; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="qmmHUbDG" Received: from [10.95.67.184] (unknown [167.220.238.152]) by linux.microsoft.com (Postfix) with ESMTPSA id C0455201BC7B; Sun, 3 Aug 2025 22:49:36 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com C0455201BC7B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1754286579; bh=A76h4RG1POnkmztMobKJragbYBbJ9FiCAa2P6uity8Y=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=qmmHUbDGeypqffd0mWMQ93VcsqWlgN9ZjnGTrjathKinmLcjJ+XwXJLnMoWFoKMIY fOM30Tf8x9eUY9vx5bjsqCGDmRpzl+ZCW2RjRIMEYEIfQWxUbpRk4WvJ3tuIxmjWNc lie0YPQI6qorxBif1z3aVscrpstOdljShj5ZMC/4= Message-ID: <5e7f02ee-6007-417b-b234-a70cec30c385@linux.microsoft.com> Date: Mon, 4 Aug 2025 11:19:34 +0530 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 6.12] Drivers: hv: Make the sysfs node size for the ring buffer dynamic To: =?UTF-8?Q?Thomas_Wei=C3=9Fschuh?= Cc: Michael Kelley , "stable@vger.kernel.org" , Wei Liu , Dexuan Cui , "K . Y . Srinivasan" , Haiyang Zhang , Long Li , Greg Kroah-Hartman , "linux-hyperv@vger.kernel.org" , "linux-kernel@vger.kernel.org" References: <20250723070200.2775-1-namjain@linux.microsoft.com> <4abf15ac-de18-48d4-9420-19d40f26fdd2@linux.microsoft.com> <8f642ca2-04dc-4d87-b120-5d128ec3202e@t-8ch.de> Content-Language: en-US From: Naman Jain In-Reply-To: <8f642ca2-04dc-4d87-b120-5d128ec3202e@t-8ch.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 8/1/2025 4:22 PM, Thomas Weißschuh wrote: > Hi Naman, > > On 2025-07-31 21:13:27+0530, Naman Jain wrote: >> On 7/30/2025 1:15 AM, Michael Kelley wrote: >>> From: Thomas Weißschuh Sent: Tuesday, July 29, 2025 11:47 AM >>>> On 2025-07-29 18:39:45+0000, Michael Kelley wrote: >>>>> From: Naman Jain Sent: Wednesday, July 23, 2025 12:02 AM > > >>>>> Unfortunately, I don't see a fix, short of backporting support for the >>>>> .bin_size function, as this is exactly the problem that function solves. >>>> >>>> It should work out in practice. (I introduced the .bin_size function) >>> >>> The race I describe is unlikely, particularly if attribute groups are created >>> once and then not disturbed. But note that the Hyper-V fcopy group can >>> get updated in a running VM via update_sysfs_group(), which also calls >>> create_files(). Such an update might marginally increase the potential for >>> the race and for getting the wrong size. Still, I agree it should work out >>> in practice. >>> >>> Michael >>> >>>> >>>> Thomas >> >> hi Thomas, >> Would it be possible to port your changes on 6.12 kernel, to avoid such >> race conditions? > > Possible, surely. But Greg has to accept it. > And you will need to do the backports. > >> Or if it has a lot of dependencies, or if you have a >> follow-up advice, please let us us know. > > Not more than mentioned before. > > > Thomas Acked. Thanks. Regards, Naman