From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.20]) (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 A1528139CEB for ; Wed, 24 Apr 2024 03:46:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.20 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713930382; cv=none; b=onj55CC2HREXl5n421ywVO59/HRsYv6fu8BFyBFIvDLri2k2C4ba5dXaUmcnz2TcysLLPmJQkSHdKvYDZh1cIMGXu9sSobrZhr6ro3ESI8BYjoAjl1l9RYAOAwsviNho0FjJsZQLFQPYUorE7DdFV30YPJyw9rUvwekQkfYdNZs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713930382; c=relaxed/simple; bh=9f1FqymkcY84ZRJChezdXFafCZhSRXFxINpKY9hyCAg=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=iF4SpOL51idn09rZpx3s04DV+G2QVDD+vzMZ16E4xjUyu9UZHGC6aessySSGN5fK0aUWR4yxqRvLXFQbz7RlI2H2QuwAhi3xCJN2mTy/AKIblzo9EqRJG74/KeQBb4Ytl+CaPIWvyxvww7Q4WNm/bpbc0NBcrJ5dR+hB2Pbu0uM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=KCLYjfXU; arc=none smtp.client-ip=198.175.65.20 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none 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.b="KCLYjfXU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1713930382; x=1745466382; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=9f1FqymkcY84ZRJChezdXFafCZhSRXFxINpKY9hyCAg=; b=KCLYjfXU8cjA2CtpG9EKsqtbOYOgPJGd04xHB15e1zlBVeHBryYm6Rp0 W8HVDpb+ue8N48LqWQ4UbUkyok783QxFe9RB2Fui7VOEl/kCRvOFzAANz yonPEBr6lq0lZOJhGPRTKXc1nrGNOhpnt8AQ7X04SLrPdvS0RUpGcsAKB fzx/3XFI1UZXSABTI5wn1uAmfjMXNf3uRUNJJudJl7aLqTTfAZva20PxV sftJeWK7p1y4+p1Y0QoVimQk6VKDBhCBrw7Ca1meC1CtoKysN9N0izXYz WzJPFxKDKEBkjOfniUT9wh3b/OumyTDngs6/EevsVF8ZOlCjWo8NFG8HA g==; X-CSE-ConnectionGUID: 65eV3iGOQKieVhdt5Ssf4w== X-CSE-MsgGUID: 90ug6WM4Sdu+NhbfLWkBVg== X-IronPort-AV: E=McAfee;i="6600,9927,11053"; a="9371170" X-IronPort-AV: E=Sophos;i="6.07,225,1708416000"; d="scan'208";a="9371170" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by orvoesa112.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Apr 2024 20:46:21 -0700 X-CSE-ConnectionGUID: UsrwtcwLSFSwEOQCIfOuhQ== X-CSE-MsgGUID: M5Zm/i5fT9SMPRe7FENI/w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,225,1708416000"; d="scan'208";a="25089694" Received: from unknown (HELO [10.239.159.127]) ([10.239.159.127]) by orviesa007.jf.intel.com with ESMTP; 23 Apr 2024 20:46:19 -0700 Message-ID: <4b3f6af7-d40e-4910-8e6d-449c59ab0dd2@linux.intel.com> Date: Wed, 24 Apr 2024 11:44:55 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: baolu.lu@linux.intel.com, David Woodhouse , Joerg Roedel , Will Deacon , Robin Murphy Subject: Re: [PATCH] iommu/intel: Use try_cmpxchg64{,_local}() in iommu.c To: Uros Bizjak , iommu@lists.linux.dev, linux-kernel@vger.kernel.org References: <20240414162454.49584-1-ubizjak@gmail.com> Content-Language: en-US From: Baolu Lu In-Reply-To: <20240414162454.49584-1-ubizjak@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 4/15/24 12:23 AM, Uros Bizjak wrote: > Replace this pattern in iommu.c: > > cmpxchg64{,_local}(*ptr, 0, new) != 0 > > .. with the simpler and faster: > > !try_cmpxchg64{,_local}(*ptr, &tmp, new) > > The x86 CMPXCHG instruction returns success in the ZF flag, so this change > saves a compare after the CMPXCHG. > > No functional change intended. > > Signed-off-by: Uros Bizjak > Cc: David Woodhouse > Cc: Lu Baolu > Cc: Joerg Roedel > Cc: Will Deacon > Cc: Robin Murphy > --- > drivers/iommu/intel/iommu.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) Patch has been queued for iommu/vt-d. Best regards, baolu