From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 9264F279DCA for ; Mon, 30 Mar 2026 13:34:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774877660; cv=none; b=RG9BUteGavZ/m8euj2zTWCvN2IgBDaqdmaoKa0fotisUkXu89w23PXXlSQlejZSQSRFcskz1bto3TSMXD3dVGNO73QjJq4Riz4mMxLLH8IAFnkF/YhfmH1oVUZ2qj8AeQ8dXXq64ZnkWEOWEDsFH7fiPR+WzAD2T4iDO0+SZx/M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774877660; c=relaxed/simple; bh=ipiZx7LpVWha3QtNT6bgTz+FuOklqbeBhtFUcqttxXw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=sP8XOA3ji8OYXJ1Fj9tT6o9C6a/n/j2p4Rm0PMAIB8+4JD4oQl3QuwJwFCnVAoYV/1fYI16NZjkuJp/gLq0QCi/ElNdQmEuAx5sqoQ+g+trxAAegwXlXiKKhZTHm+nlv25QIjz1f0frJMf/8NreHrz+nFPvCf/nQ43/3jO+Yd5w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=bmb/NneG; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="bmb/NneG" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id CA03C3562; Mon, 30 Mar 2026 06:34:11 -0700 (PDT) Received: from J2N7QTR9R3 (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 618E73F7D8; Mon, 30 Mar 2026 06:34:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1774877657; bh=ipiZx7LpVWha3QtNT6bgTz+FuOklqbeBhtFUcqttxXw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bmb/NneGn7sGSiLZfeWaVTKydAzJOXasQAu8NeaHWfzXKYL92gxTR1Uosupv7L7r5 GJ21WD29Pc7+dlVYBxwvechBhl7fE+bukc6M6qJBZinm8Mpdwz8K7Y+96VVP/Z9niN Zoeyqv0J+zo9OwYDzp5cjvt4mmP6VJ0CGe7Va4iM= Date: Mon, 30 Mar 2026 14:34:13 +0100 From: Mark Rutland To: Thomas Gleixner Cc: LKML , Mathieu Desnoyers , =?utf-8?B?QW5kcsOo?= Almeida , Sebastian Andrzej Siewior , Carlos O'Donell , Peter Zijlstra , Florian Weimer , Rich Felker , Torvald Riegel , Darren Hart , Ingo Molnar , Davidlohr Bueso , Arnd Bergmann , "Liam R . Howlett" , Uros Bizjak , Thomas =?utf-8?Q?Wei=C3=9Fschuh?= Subject: Re: [patch V3 06/14] x86: Select ARCH_MEMORY_ORDER_TOS Message-ID: References: <20260330114212.927686587@kernel.org> <20260330120117.467037069@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@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: <20260330120117.467037069@kernel.org> On Mon, Mar 30, 2026 at 02:02:31PM +0200, Thomas Gleixner wrote: > The generic unsafe_atomic_store_release_user() implementation does: > > if (!IS_ENABLED(CONFIG_ARCH_MEMORY_ORDER_TOS)) > smp_mb(); > unsafe_put_user(); > > As x86 implements Total Store Order (TOS) which means stores imply release, > select ARCH_MEMORY_ORDER_TOS to avoid the unnecessary smp_mb(). > > Signed-off-by: Thomas Gleixner > Reviewed-by: André Almeida > --- > V3: Rename to TOS - Peter As on the last patch, shouldn't that be TSO? Mark > V2: New patch > --- > arch/x86/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -114,6 +114,7 @@ config X86 > select ARCH_HAS_ZONE_DMA_SET if EXPERT > select ARCH_HAVE_NMI_SAFE_CMPXCHG > select ARCH_HAVE_EXTRA_ELF_NOTES > + select ARCH_MEMORY_ORDER_TOS > select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE > select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI > select ARCH_MIGHT_HAVE_PC_PARPORT >