From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=198.175.65.9 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794247476; b=XwaSy/VPti6F65uFmaE+WrlYWaAX/vjU3uyahZ3TkFD8lMk4ABrTA/dWge4YWs4a9R3d fFQbk0HB3eZBPEgGtt4shn2DMVVF4f5xwpwzaAgxBGTpva+BdyHwDKc6LOCKtpYOeXvXz +vdnNZNSrrsCTkzvH6uJm0KeCEoaehQWPklXFL/t24XPTKEHGTSjmDvvlFAQ6NP+Vx3Cl qGoVfKeZU/F8kOOr+XY8Cql1A+FSR5/HPjghLLnlGN/AvHRqKVQzSczdlH6E0BZyxxs13 qZFWzOzKozYB/VABRDfam+GmR0xnOxHZRXVyoyJ1ULCn/nKn33ui8ijf6kYDxJZKbuA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794247476; h=DMARC-Filter:DKIM-Signature:X-CSE-ConnectionGUID:X-CSE-MsgGUID: X-IronPort-AV:X-IronPort-AV:Received:X-CSE-ConnectionGUID: X-CSE-MsgGUID:X-ExtLoop1:X-IronPort-AV:Received:Date:From:To:Cc: Subject:Message-ID:References:MIME-Version:Content-Type: Content-Disposition:In-Reply-To:Organization; bh=qiJ7xcOjNXyII+yiz+zZqioSWqQJ99faJ7nKZxybbn4=; b=r+FPk2vfWj2JE+wbBBTutNXJO989kp6eR29QQ5RNyWtsNvKZypgColGPgLI0somZsbY5 u7F6Ozf/AwiSajX97lSxOfLF/PspAThXKeHErEGkq3sPlX2a1dHQIppCuIR8WDxDimbXU lCOJID+OfpvPFSJz6H6/a3OvDb8nulQs/03WV07ivtGx6NarnsUntbnr0XFdDsfcEZWlx hM2xPzR8C7woa40pC+CG+Ttwz9zwPMid+pmnbNfYMyNVgEukCdY3OG4tzrqTBBR1eAGhH 43iJ4wqK2NIwcGa0wtBgle2KVjh9AX0oScNCAJkF8tpRIHs3D5gWEqdzhbpQ3SzKyVw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=JfS6SNA+; arc=none smtp.remote-ip=198.175.65.9 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.9]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 370BF606A31C; Mon, 9 Nov 2026 18:04:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 370BF606A31C Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=JfS6SNA+ DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1794247476; x=1825783476; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=PwpaDGj8GyOkiCWitGngWvUI379OhhscqTT8voYCpFk=; b=JfS6SNA+qxXuwLaAAHsrkfwwaIxSMC2FHqxirqlVSo+nEijMqBx8qfHx V1HKA9JhNVti9VHRvGymsSeDjN7m9OSU+187AJpmGzayjAJlUwppirasN nYOvrRNlWb9X16tGkGNv1p9qTd4Vz7vNL/AKZNUaLrjT6atV1x4JNCu+e 9gEYKgdVQ5hAfHD5+u0PZmgQ4fs6Ghq1tpZbd6PX2Yt8376GoQ5yXAQ7r lvjgWCuGHB7lU2mWp1WQCoieYRVfxdprj7yX/WKQic/bS/5gkguj2203u a13w4ZFXd2HmNpDtfoa5lPNc4dKp/ffvuZYHC+U82NbXttLbg9FiPbiil g==; X-CSE-ConnectionGUID: T1hYD3iGSkSv7h+Bb6yPDQ== X-CSE-MsgGUID: aGj4kNATR+eqhaKmezj5ng== X-IronPort-AV: E=McAfee;i="6800,10657,11961"; a="2877641" X-IronPort-AV: E=Sophos;i="6.27,204,1787036400"; d="scan'208";a="2877641" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Nov 2026 10:04:36 -0800 X-CSE-ConnectionGUID: hZ6m/+OiTE2G7CON2L9ZNg== X-CSE-MsgGUID: XoLv/KaHTYqwEe1jgRTFtQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,204,1787036400"; d="scan'208";a="7790832" Received: from amilburn-desk.amilburn-desk (HELO localhost) ([10.245.244.144]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Nov 2026 10:04:34 -0800 Date: Mon, 9 Nov 2026 20:04:31 +0200 From: Andy Shevchenko To: Bartosz Golaszewski Cc: Bartosz Golaszewski , Linus Walleij , linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] gpiolib: synchronize updates of descriptor labels Message-ID: References: <20261105-gpiolib-set-desc-label-corruption-v1-1-fa84726ceac0@oss.qualcomm.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo On Fri, Nov 06, 2026 at 10:22:07AM +0100, Bartosz Golaszewski wrote: > On Thu, Nov 05, 2026 at 04:53:10PM +0200, Andy Shevchenko wrote: > > On Thu, Nov 05, 2026 at 02:23:45PM +0100, Bartosz Golaszewski wrote: > > > desc_set_label() swaps desc->label with rcu_replace_pointer() but > > > without any synchronization of concurrent updates. The swap is a plain > > > read + write: two threads can observe the same old label and then call > > > > s/call// > > Why? It's "call $function_name" which happens to be call_srcu(). Because with that kind of name it sounds not good (tautological). > > > call_scru() on the same SRCU head corrupting the state of the chain. -- With Best Regards, Andy Shevchenko