From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.11]) (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 BBEC21607B2 for ; Fri, 10 May 2024 09:13:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715332416; cv=none; b=Qmeqv4IEyyjI+3sFoNgmeOTyKFwP244GzswMAd2rME8hhWAUlJL8i0Y12P8SYWTQnQxbBPmUKRHR1kWkV023Zbi+RqSChXKu4ruplTMMUXTTyKvjeWddH5gHd3/jKAchpgLjNTSkyso3dNxVFxpODTJBtbPDeLws8k5S+c7Kho4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715332416; c=relaxed/simple; bh=TF+PTbkgSx0ZnPRn+1LyMRtzCYZzLtwMrn37b5euxao=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=QDKqtsJsX4V8BAhGUqlw+Ik6q0OxSI3aosrHR71OB8Mgt9obsKKWnnHJOpsb5noufGKJOlrezSFNrIMMsBFiekYni2J0raCIY2kZDlXvTSn4/c5uS9fgCeTjRKdns0KsnRPHpcpWqyLBSID7nfuVcyUM/JnzfFsfqrbi0kUsadY= 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=XhhkvkLM; arc=none smtp.client-ip=198.175.65.11 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="XhhkvkLM" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1715332415; x=1746868415; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=TF+PTbkgSx0ZnPRn+1LyMRtzCYZzLtwMrn37b5euxao=; b=XhhkvkLM2QzrS6snlZoF+lY7ZW7xlc4lmW80d8+i/guPgSrTPOcmOvYT mkvRp4XMXuL+xK9h3YFOJbcoBK9NQC7IiKMKlSEaGa/Ts98Lh2uBm8g+x 3u4A1tD7VT22M1maBswS5H2CLV21eDLI3qDO1If0dYVt8oan2hNQOhQb7 oYq5IqztdP3zMdZ5kroA/p/3V5oHVx2XMiqpYRXzRfIlcmKMfHiz+DEky tzMrIDAPKCpLWUBr9WzEeCRCbmd3D1TqgQRoEP4WCLlFTGWCVhF7IId/T KEPemlJNi1hXAtcfNkaJNNpCvAeqhmCQowoubRnIjvzY2a+m7lF1nFmrY g==; X-CSE-ConnectionGUID: 6AqTP8RWTJ29EELvlo2tiw== X-CSE-MsgGUID: kX/rK7NTRxybQH3mdnEsFw== X-IronPort-AV: E=McAfee;i="6600,9927,11068"; a="21879095" X-IronPort-AV: E=Sophos;i="6.08,150,1712646000"; d="scan'208";a="21879095" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by orvoesa103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 May 2024 02:13:35 -0700 X-CSE-ConnectionGUID: HlxxGN5LQIqbfopkgkxtpA== X-CSE-MsgGUID: rZ7SJb6RSguTrlxaCy7EDA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.08,150,1712646000"; d="scan'208";a="29555229" Received: from blu2-mobl.ccr.corp.intel.com (HELO [10.124.237.100]) ([10.124.237.100]) by fmviesa009-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 May 2024 02:13:30 -0700 Message-ID: Date: Fri, 10 May 2024 17:13:29 +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, Kevin Tian , Joerg Roedel , Will Deacon , Robin Murphy , Jean-Philippe Brucker , Nicolin Chen , Yi Liu , Jacob Pan , Joel Granados , iommu@lists.linux.dev, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 5/9] iommufd: Add iommufd fault object To: Jason Gunthorpe References: <20240430145710.68112-1-baolu.lu@linux.intel.com> <20240430145710.68112-6-baolu.lu@linux.intel.com> <20240508002242.GP4718@ziepe.ca> Content-Language: en-US From: Baolu Lu In-Reply-To: <20240508002242.GP4718@ziepe.ca> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2024/5/8 8:22, Jason Gunthorpe wrote: > On Tue, Apr 30, 2024 at 10:57:06PM +0800, Lu Baolu wrote: >> +static ssize_t iommufd_fault_fops_read(struct file *filep, char __user *buf, >> + size_t count, loff_t *ppos) >> +{ >> + size_t fault_size = sizeof(struct iommu_hwpt_pgfault); >> + struct iommufd_fault *fault = filep->private_data; >> + struct iommu_hwpt_pgfault data; >> + struct iommufd_device *idev; >> + struct iopf_group *group; >> + struct iopf_fault *iopf; >> + size_t done = 0; >> + int rc; >> + >> + if (*ppos || count % fault_size) >> + return -ESPIPE; >> + >> + mutex_lock(&fault->mutex); >> + while (!list_empty(&fault->deliver) && count > done) { >> + group = list_first_entry(&fault->deliver, >> + struct iopf_group, node); >> + >> + if (list_count_nodes(&group->faults) * fault_size > count - done) >> + break; > > Can this list_count be precomputed when we build the fault group? Yes. Done. > >> + >> + idev = group->attach_handle->idev; >> + if (!idev) >> + break; > > This check should be done before adding the fault to the linked > list. See my other note about the race. Done. > >> + >> + rc = xa_alloc(&idev->faults, &group->cookie, group, >> + xa_limit_32b, GFP_KERNEL); >> + if (rc) >> + break; > > This error handling is not quite right, if done == 0 then this should > return rc. > > >> + >> + list_for_each_entry(iopf, &group->faults, list) { >> + iommufd_compose_fault_message(&iopf->fault, >> + &data, idev, >> + group->cookie); >> + rc = copy_to_user(buf + done, &data, fault_size); >> + if (rc) { >> + xa_erase(&idev->faults, group->cookie); >> + break; > > Same here > > (same comment on the write side too) All fixed. Thank you! Best regards, baolu