From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from todd.t-8ch.de (todd.t-8ch.de [159.69.126.157]) (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 11E6C2B9A5; Fri, 1 Aug 2025 10:52:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.69.126.157 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754045541; cv=none; b=pLJ7iszFIHsX+GeDqW3o75gejYXmlANgouD2VRuAdTsoG2zph6cPHd8Ffc44cebOmQbihQBpJFaTwhscz5o/LIvynOCEsu1UVCAuZS/vKjEJhkZK68WtCIk1BpGyg73hCY/xR2IUgBa3//5SgqULnlcw/nBOXAyM6ybJMu+XMnM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754045541; c=relaxed/simple; bh=Pq4K8Lbc77aD4fbd+31DfDceIFn4GKRekMM7Bcbhbaw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=I3IUdzDsmkPL0JQea9fGadrN9nXart+x8n0R1OsoYUByik7WSLGoYAgeIotAP3ELOniLkyKNnDh7Ez/vrggKRyQTnfbvKZw0ip1VjRZYtiFNrZeenIxogn8vJmhHQJpPNfOmIgByRwXcTJEWrOUVJqmc3H6TCwUBCfDTFLEMpvc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=weissschuh.net; spf=pass smtp.mailfrom=weissschuh.net; dkim=pass (1024-bit key) header.d=weissschuh.net header.i=@weissschuh.net header.b=MFPtCz9E; arc=none smtp.client-ip=159.69.126.157 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=weissschuh.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=weissschuh.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=weissschuh.net header.i=@weissschuh.net header.b="MFPtCz9E" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=weissschuh.net; s=mail; t=1754045535; bh=Pq4K8Lbc77aD4fbd+31DfDceIFn4GKRekMM7Bcbhbaw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MFPtCz9E09oRpuzc89z+FHmxx7ew/EaVMdUB1wrjQVihZpQ3HrUYJLrAlxozJeVF1 uK4CVbyUWqTAersD5/jIxjOlXzs7g3Bfrnwx2JIEUw5/UJ7UZFJcOla5v+ihZAUMl5 zhL/ZJwt4hWKd2UP2FPe6lmPk8oC88DdGLyRC/V0= Date: Fri, 1 Aug 2025 12:52:15 +0200 From: Thomas =?utf-8?Q?Wei=C3=9Fschuh?= To: Naman Jain 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" Subject: Re: [PATCH 6.12] Drivers: hv: Make the sysfs node size for the ring buffer dynamic Message-ID: <8f642ca2-04dc-4d87-b120-5d128ec3202e@t-8ch.de> References: <20250723070200.2775-1-namjain@linux.microsoft.com> <4abf15ac-de18-48d4-9420-19d40f26fdd2@linux.microsoft.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4abf15ac-de18-48d4-9420-19d40f26fdd2@linux.microsoft.com> 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