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[2620:137:e000::3:7]) by mx.google.com with ESMTPS id s9-20020a170902ea0900b001c9c108bf6esi3682295plg.387.2023.11.01.10.27.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Nov 2023 10:27:17 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) client-ip=2620:137:e000::3:7; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 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 93243813989F; Wed, 1 Nov 2023 10:26:59 -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 S1344449AbjKAR04 (ORCPT + 34 others); Wed, 1 Nov 2023 13:26:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36848 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231966AbjKAR0x (ORCPT ); Wed, 1 Nov 2023 13:26:53 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DA5EEE4; Wed, 1 Nov 2023 10:26:50 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63BDEC433C8; Wed, 1 Nov 2023 17:26:50 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.96) (envelope-from ) id 1qyEzR-00EZs7-0m; Wed, 01 Nov 2023 13:26:49 -0400 Message-ID: <20231101172649.049758712@goodmis.org> User-Agent: quilt/0.66 Date: Wed, 01 Nov 2023 13:25:42 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Andrew Morton , stable@vger.kernel.org, Ajay Kaher Subject: [PATCH v6 1/8] eventfs: Remove "is_freed" union with rcu head References: <20231101172541.971928390@goodmis.org> MIME-Version: 1.0 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]); Wed, 01 Nov 2023 10:26:59 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1781383443935468105 X-GMAIL-MSGID: 1781383443935468105 From: "Steven Rostedt (Google)" The eventfs_inode->is_freed was a union with the rcu_head with the assumption that when it was on the srcu list the head would contain a pointer which would make "is_freed" true. But that was a wrong assumption as the rcu head is a single link list where the last element is NULL. Instead, split the nr_entries integer so that "is_freed" is one bit and the nr_entries is the next 31 bits. As there shouldn't be more than 10 (currently there's at most 5 to 7 depending on the config), this should not be a problem. Cc: stable@vger.kernel.org Cc: Ajay Kaher Fixes: 63940449555e7 ("eventfs: Implement eventfs lookup, read, open functions") Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) --- Changes since v5: https://lkml.kernel.org/r/20231031223419.935276916@goodmis.org - Resynced for this patch series fs/tracefs/event_inode.c | 2 ++ fs/tracefs/internal.h | 6 +++--- 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 9f612a8f009d..1ce73acf3df0 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -824,6 +824,8 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, struct list_head *head, eventfs_remove_rec(ei_child, head, level + 1); } + ei->is_freed = 1; + list_del_rcu(&ei->list); list_add_tail(&ei->del_list, head); } diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h index 64fde9490f52..c7d88aaa949f 100644 --- a/fs/tracefs/internal.h +++ b/fs/tracefs/internal.h @@ -23,6 +23,7 @@ struct tracefs_inode { * @d_parent: pointer to the parent's dentry * @d_children: The array of dentries to represent the files when created * @data: The private data to pass to the callbacks + * @is_freed: Flag set if the eventfs is on its way to be freed * @nr_entries: The number of items in @entries */ struct eventfs_inode { @@ -38,14 +39,13 @@ struct eventfs_inode { * Union - used for deletion * @del_list: list of eventfs_inode to delete * @rcu: eventfs_inode to delete in RCU - * @is_freed: node is freed if one of the above is set */ union { struct list_head del_list; struct rcu_head rcu; - unsigned long is_freed; }; - int nr_entries; + unsigned int is_freed:1; + unsigned int nr_entries:31; }; static inline struct tracefs_inode *get_tracefs(const struct inode *inode)