From patchwork Tue Oct 31 22:33:26 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 16120 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:abcd:0:b0:403:3b70:6f57 with SMTP id f13csp61468vqx; Tue, 31 Oct 2023 15:34:27 -0700 (PDT) X-Google-Smtp-Source: AGHT+IETzQOo8Ykr8aFl7aLHmyraxRkZbpIr9T74Xgb8mdk5pzVU2J5Pi6oq5ykRt6IJ7DGbylbX X-Received: by 2002:a17:903:32d1:b0:1cc:3bc9:b924 with SMTP id i17-20020a17090332d100b001cc3bc9b924mr7728624plr.25.1698791667098; Tue, 31 Oct 2023 15:34:27 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1698791667; cv=none; d=google.com; s=arc-20160816; b=q+Lm0ZHAxkp7liTjmAhoBD3E1nHkXaIoD2tiDzj7xTk+M2NoX+kgD3YGIcLc5ozKBX xhg+o4hXeifXZAJ8+MmBKFsTerjiiAUNiPfHb0bzBs3o7eyxrXNBtthAYrdSAluA7zzN bVgNLoLFeqJ+er4cB9Q3Li8vYVSFdlcG5iwIzyOxoZulB0ebPkI4wCZ2i9uS578CsnnZ IKgVnarDIL3XUAdxmPzOYGdPXOruBYXVTUOAFuttLRxzmHwozCUhje4PBNcVYsMfWIcX vzVmA+i8GAmFWGy1ra2H6prAB62Y/HImYLV9IJxnzIDcV5e9d6XnvjNxaZkTdjucPEYP 444A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:subject:cc:to:from:date:user-agent:message-id; bh=bjMWbTEarNgJj9G8neamDfPdeycmppM09b6A4kB0JIs=; fh=p9qaSGjxjg7fXhZ2SPcVaCB443dWE9yY5/nXWowH5kM=; b=edQ4KWjkh/l28a6VLS9scTnLaYfb6vKmZ1COgV1oKpENu7ZSgLOflY4t0XjvY22Qyd wieRCnEXNBaiP1ZDXFvG7lkZzb1KYJnY5HTjTODzqAmVay2tZcClg07q5WoSaOQ96x7T bBA2P78eyBuL9N5EcNUemSN8r4sIe08xSedhFl/VpJyCLuV//gDFaRi+HAulhkq21vjW KThapXLCyy1xj6cqXdV73XTGnAouVzVfCN3i96d53zFtebtIe+7ylakN1etYfqRhuHuT 1mQSr4b63RU/usF8NdBGjQ81QVqb4IojFLMdl1d4YlyMCAnE4Icj5O4islXpbBVmp/wm J+jA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from snail.vger.email (snail.vger.email. [23.128.96.37]) by mx.google.com with ESMTPS id le3-20020a170902fb0300b001c5e0672f53si1606894plb.466.2023.10.31.15.34.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 31 Oct 2023 15:34:27 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) client-ip=23.128.96.37; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by snail.vger.email (Postfix) with ESMTP id E87028068869; Tue, 31 Oct 2023 15:34:25 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at snail.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346796AbjJaWeZ (ORCPT + 33 others); Tue, 31 Oct 2023 18:34:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37598 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344887AbjJaWeY (ORCPT ); Tue, 31 Oct 2023 18:34:24 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F925F3 for ; Tue, 31 Oct 2023 15:34:21 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 19C75C433C8; Tue, 31 Oct 2023 22:34:21 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.96) (envelope-from ) id 1qxxJT-00EPgI-2v; Tue, 31 Oct 2023 18:34:19 -0400 Message-ID: <20231031223326.794680978@goodmis.org> User-Agent: quilt/0.66 Date: Tue, 31 Oct 2023 18:33:26 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Ajay Kaher , Andrew Morton Subject: [PATCH v5 0/7] eventfs: Fixing dynamic creation X-Spam-Status: No, score=-4.0 required=5.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (snail.vger.email [0.0.0.0]); Tue, 31 Oct 2023 15:34:26 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1781300868856308339 X-GMAIL-MSGID: 1781312170974830177 I found an issue with using a union between the rcu list head and the "is_freed" boolean (word). That is, rcu list is a single link list where the last element has a NULL pointer. That means, if the eventfs_inode is the last element (which it likely will be) it will not have its flag set to is_free. Instead use a bit from nr_entries to be the is_freed flag. Changes since v4: https://lore.kernel.org/linux-trace-kernel/20231031193109.018322397@goodmis.org/ - Updated on top of the change to separate out is_freed from the union - Add another fix to only delete the eventfs_inode after the last dentry has cleared its reference (there's more races there without doing that) - Make the top level eventfs directory the same as the rest in being removed. Steven Rostedt (Google) (7): eventfs: Remove "is_freed" union with rcu head eventfs: Have a free_ei() that just frees the eventfs_inode eventfs: Test for ei->is_freed when accessing ei->dentry eventfs: Save ownership and mode eventfs: Hold eventfs_mutex when calling callback functions eventfs: Delete eventfs_inode when the last dentry is freed eventfs: Remove special processing of dput() of events directory ---- fs/tracefs/event_inode.c | 431 +++++++++++++++++++++++++++++++---------------- fs/tracefs/internal.h | 27 ++- include/linux/tracefs.h | 43 +++++ 3 files changed, 353 insertions(+), 148 deletions(-)