From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,MSGID_FROM_MTA_HEADER,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DC4F2C2D0A3 for ; Wed, 4 Nov 2020 22:17:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6A6982080D for ; Wed, 4 Nov 2020 22:17:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="AUI0+tgb"; dkim=pass (1024-bit key) header.d=fb.onmicrosoft.com header.i=@fb.onmicrosoft.com header.b="BH1bZFPs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731876AbgKDWRf (ORCPT ); Wed, 4 Nov 2020 17:17:35 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:58366 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730724AbgKDWQS (ORCPT ); Wed, 4 Nov 2020 17:16:18 -0500 Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 0A4MFwm1005890; Wed, 4 Nov 2020 14:16:00 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=date : from : to : cc : subject : message-id : references : content-type : in-reply-to : mime-version; s=facebook; bh=CjRuBlU2QowrJA1+D9q9Bybb6iRBfVNSHW+OtLmxMyY=; b=AUI0+tgbPbIc1u9IWztwp6byQtQMsmu/x2sT241lQ77ODPoJvqRbMrWpF1gWCv57aO97 OxbMVFFhw3ZcdvH9JT3JMgSwbuQZHjhKv1ijXdInr4a4pn6GdLdd4rYYYQqQDO/my5Go dIp7RU2DB9GsNHktxIUSoAel2YP+0cRwW+c= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 34kf5c6ctt-5 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Wed, 04 Nov 2020 14:16:00 -0800 Received: from NAM10-MW2-obe.outbound.protection.outlook.com (100.104.31.183) by o365-in.thefacebook.com (100.104.36.100) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Wed, 4 Nov 2020 14:15:44 -0800 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=B60/kzKukYLNTT3O84Y2fQ7jljUmigz+Zg6OTSITDCj1hwjS0dMdYS2GPjx20jS7Y9beE45mfIo4FcJZIaNupQRxKtc0++rZR8K4+O8HxFSrRAyKZ2U6zICpDHEtmVTDxHr5NI1p7+i0bvvUT5ZoNMsBNNTg1EYDVqjZTMGriuqW7jEB6uxH7jClHadgCRSU3ZC8VUiVQBTnvBHGz7qasjH34R/5rSw9aXHH1ZTYA0pt7oSUW1ScmlH+l5wqb0sFXtiYaFPrze+Duihg1zfuPOkaFZ7vx5m+Bc4wSVlod91VFqePyjtyhSf71jdPdkEOjLiWwVHhXfalVohr6MG01w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=CjRuBlU2QowrJA1+D9q9Bybb6iRBfVNSHW+OtLmxMyY=; b=BYZQv142+63QkPjCnfbxXKDiKWZR6SvjcLsM+xizG61wWt8XOU79bFj6PfDB8ssTQWnxTTp+t1aMvbxKrYsL0Hbnp1pM1oMIu3LzKJdQAqLB6Dhg3IiGtYWIY0aQGrLC7iAgwfUNeK3RMQlqNiNxc8/6JYnqCYr0QFaKqtuztAEcmebzMx5+ji3X5sU+zFRnWr+CWcuZNBeLX9MTAoPRoe9XZEuhbxEApgj7v0zW4KC6rNfr4s0mmP7tXVekElMriWxAytPvdgQET9Xhc5M0CZwg82M6RhpDDSmMCR4N381btilMvUF5sg6eCwwZvsq7Rdhi3mgKWqRA6nCG5isvBQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=fb.com; dmarc=pass action=none header.from=fb.com; dkim=pass header.d=fb.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.onmicrosoft.com; s=selector2-fb-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=CjRuBlU2QowrJA1+D9q9Bybb6iRBfVNSHW+OtLmxMyY=; b=BH1bZFPs7EvliHlx6+VrOvcqH0k64TndxB/o3dPwGQ65IHdihWy+fmVR8mH4uEqoijkfv0wVpd7EhGYRIRVFcBuoRUsNGU6/bN6d2Sg07tS2xCMNlIXdcmwRkQlMqduwNcF8UtuxlEeE8yKYJJilu8K4YkNPsZ39UUFFZKo7K/c= Authentication-Results: chromium.org; dkim=none (message not signed) header.d=none;chromium.org; dmarc=none action=none header.from=fb.com; Received: from BY5PR15MB3571.namprd15.prod.outlook.com (2603:10b6:a03:1f6::32) by SJ0PR15MB4235.namprd15.prod.outlook.com (2603:10b6:a03:2e3::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3499.27; Wed, 4 Nov 2020 22:15:41 +0000 Received: from BY5PR15MB3571.namprd15.prod.outlook.com ([fe80::bc1d:484f:cb1f:78ee]) by BY5PR15MB3571.namprd15.prod.outlook.com ([fe80::bc1d:484f:cb1f:78ee%4]) with mapi id 15.20.3499.032; Wed, 4 Nov 2020 22:15:41 +0000 Date: Wed, 4 Nov 2020 14:15:35 -0800 From: Martin KaFai Lau To: KP Singh CC: , , Song Liu , Alexei Starovoitov , Daniel Borkmann , Paul Turner , Jann Horn , Hao Luo Subject: Re: [PATCH bpf-next v3 1/9] bpf: Implement task local storage Message-ID: <20201104221526.dv6qfpfp5lk2t7zw@kafai-mbp.dhcp.thefacebook.com> References: <20201104164453.74390-1-kpsingh@chromium.org> <20201104164453.74390-2-kpsingh@chromium.org> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201104164453.74390-2-kpsingh@chromium.org> X-Originating-IP: [2620:10d:c090:400::5:3041] X-ClientProxiedBy: CO1PR15CA0059.namprd15.prod.outlook.com (2603:10b6:101:1f::27) To BY5PR15MB3571.namprd15.prod.outlook.com (2603:10b6:a03:1f6::32) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from kafai-mbp.dhcp.thefacebook.com (2620:10d:c090:400::5:3041) by CO1PR15CA0059.namprd15.prod.outlook.com (2603:10b6:101:1f::27) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3499.18 via Frontend Transport; Wed, 4 Nov 2020 22:15:40 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 1c720cff-464c-4b54-634f-08d8810f2a7d X-MS-TrafficTypeDiagnostic: SJ0PR15MB4235: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-FB-Source: Internal X-MS-Oob-TLC-OOBClassifiers: OLM:8273; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: RspPk5v+L4+ISWS79A55JWnF4ylhrlL45hoPN9am/c/L3CLlhS5u6hYFYBC7jSZy32TBJeSFYut3xG4KCHcj47dSOxjthq1Zpvv5U5xbvRhLthzS5Fle0/7HpUnD3ue5mw9POB2cQ0Uyxq+Dp2Gx5FWbGeqzlDmvMBO0dDydK0bWLCJdCtFCUarx5TdJQ+UvN8uMa5DQgANoE2H3Wt0GHzKX+2tiWYyZsWx405B8543edatOPNM6unAjXHEfNCDXeJQacbr294BGwiq6qSnKQF9n++FXEkjyFF1d2LttpCD9qnjeQdIVP6DMkVOb6VNt X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BY5PR15MB3571.namprd15.prod.outlook.com;PTR:;CAT:NONE;SFS:(346002)(39860400002)(396003)(376002)(136003)(366004)(9686003)(6666004)(8936002)(8676002)(6916009)(6506007)(4326008)(186003)(55016002)(86362001)(16526019)(66946007)(478600001)(5660300002)(2906002)(7696005)(66476007)(83380400001)(66556008)(1076003)(54906003)(316002)(52116002);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData: 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 X-MS-Exchange-CrossTenant-Network-Message-Id: 1c720cff-464c-4b54-634f-08d8810f2a7d X-MS-Exchange-CrossTenant-AuthSource: BY5PR15MB3571.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Nov 2020 22:15:41.2826 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: pp5V/rFICkyzpn1iSUEfnAGIuZTEYF6XE2KY/yDENFqh68cZO3qkN8+G6aq4TKrA X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR15MB4235 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312,18.0.737 definitions=2020-11-04_15:2020-11-04,2020-11-04 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 adultscore=0 spamscore=0 clxscore=1015 phishscore=0 impostorscore=0 mlxscore=0 mlxlogscore=634 suspectscore=1 priorityscore=1501 malwarescore=0 bulkscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011040158 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, Nov 04, 2020 at 05:44:45PM +0100, KP Singh wrote: [ ... ] > +static void *bpf_pid_task_storage_lookup_elem(struct bpf_map *map, void *key) > +{ > + struct bpf_local_storage_data *sdata; > + struct task_struct *task; > + unsigned int f_flags; > + struct pid *pid; > + int fd, err; > + > + fd = *(int *)key; > + pid = pidfd_get_pid(fd, &f_flags); > + if (IS_ERR(pid)) > + return ERR_CAST(pid); > + > + /* We should be in an RCU read side critical section, it should be safe > + * to call pid_task. > + */ > + WARN_ON_ONCE(!rcu_read_lock_held()); > + task = pid_task(pid, PIDTYPE_PID); > + if (!task) { > + err = -ENOENT; > + goto out; > + } > + > + sdata = task_storage_lookup(task, map, true); > + put_pid(pid); > + return sdata ? sdata->data : NULL; > +out: > + put_pid(pid); > + return ERR_PTR(err); > +} > + > +static int bpf_pid_task_storage_update_elem(struct bpf_map *map, void *key, > + void *value, u64 map_flags) > +{ > + struct bpf_local_storage_data *sdata; > + struct task_struct *task; > + unsigned int f_flags; > + struct pid *pid; > + int fd, err; > + > + fd = *(int *)key; > + pid = pidfd_get_pid(fd, &f_flags); > + if (IS_ERR(pid)) > + return PTR_ERR(pid); > + > + /* We should be in an RCU read side critical section, it should be safe > + * to call pid_task. > + */ > + WARN_ON_ONCE(!rcu_read_lock_held()); > + task = pid_task(pid, PIDTYPE_PID); > + if (!task) { > + err = -ENOENT; > + goto out; > + } > + > + sdata = bpf_local_storage_update( > + task, (struct bpf_local_storage_map *)map, value, map_flags); It seems the task is protected by rcu here and the task may be going away. Is it ok? or the following comment in the later "BPF_CALL_4(bpf_task_storage_get, ...)" is no longer valid? /* This helper must only called from where the task is guaranteed * to have a refcount and cannot be freed. */ > + > + err = PTR_ERR_OR_ZERO(sdata); > +out: > + put_pid(pid); > + return err; > +} > + [ ... ] > +BPF_CALL_4(bpf_task_storage_get, struct bpf_map *, map, struct task_struct *, > + task, void *, value, u64, flags) > +{ > + struct bpf_local_storage_data *sdata; > + > + if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE)) > + return (unsigned long)NULL; > + > + /* explicitly check that the task_storage_ptr is not > + * NULL as task_storage_lookup returns NULL in this case and > + * bpf_local_storage_update expects the owner to have a > + * valid storage pointer. > + */ > + if (!task_storage_ptr(task)) > + return (unsigned long)NULL; > + > + sdata = task_storage_lookup(task, map, true); > + if (sdata) > + return (unsigned long)sdata->data; > + > + /* This helper must only called from where the task is guaranteed > + * to have a refcount and cannot be freed. > + */ > + if (flags & BPF_LOCAL_STORAGE_GET_F_CREATE) { > + sdata = bpf_local_storage_update( > + task, (struct bpf_local_storage_map *)map, value, > + BPF_NOEXIST); > + return IS_ERR(sdata) ? (unsigned long)NULL : > + (unsigned long)sdata->data; > + } > + > + return (unsigned long)NULL; > +} [ ... ] > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > index 8f50c9c19f1b..f3fe9f53f93c 100644 > --- a/kernel/bpf/syscall.c > +++ b/kernel/bpf/syscall.c > @@ -773,7 +773,8 @@ static int map_check_btf(struct bpf_map *map, const struct btf *btf, > map->map_type != BPF_MAP_TYPE_ARRAY && > map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE && > map->map_type != BPF_MAP_TYPE_SK_STORAGE && > - map->map_type != BPF_MAP_TYPE_INODE_STORAGE) > + map->map_type != BPF_MAP_TYPE_INODE_STORAGE && > + map->map_type != BPF_MAP_TYPE_TASK_STORAGE) This is to enable spin lock support in a map's value. Without peeking patch 5, I was confused a bit here. It seems patch 5 was missed when inode storage was added. > return -ENOTSUPP; > if (map->spin_lock_off + sizeof(struct bpf_spin_lock) > > map->value_size) {