linux-kernel - [PATCH v2] eventfs: Initialize the tracefs inode properly

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Message-ID: <20240130152608.6109e7b0@gandalf.local.home>
Date: Tue, 30 Jan 2024 15:26:08 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: LKML <linux-kernel@...r.kernel.org>, Linux Trace Kernel
 <linux-trace-kernel@...r.kernel.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>, Masami Hiramatsu
 <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Christian Brauner <brauner@...nel.org>, Al Viro <viro@...IV.linux.org.uk>
Subject: [PATCH v2] eventfs: Initialize the tracefs inode properly

From: Linus Torvalds <torvalds@...ux-foundation.org>

The tracefs-specific fields in the inode were not initialized before the
inode was exposed to others through the dentry with 'd_instantiate()'.

Move the field initializations up to before the d_instantiate.

Cc: stable@...r.kernel.org
Fixes: 5790b1fb3d672 ("eventfs: Remove eventfs_file and just use eventfs_inode")
Reported-by: kernel test robot <oliver.sang@...el.com>
Closes: https://lore.kernel.org/oe-lkp/202401291043.e62e89dc-oliver.sang@intel.com
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
Changes since v1: https://lore.kernel.org/linux-trace-kernel/20240130190355.11486-2-torvalds@linux-foundation.org

- Since another patch zeroed out the entire tracefs_inode, there's no need
  to initialize any of its fields to NULL.
  (see https://lore.kernel.org/linux-trace-kernel/20240130151737.6e97ae00@gandalf.local.home/)

 fs/tracefs/event_inode.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 1c3dd0ad4660..824b1811e342 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -370,6 +370,8 @@ static struct dentry *create_dir(struct eventfs_inode *ei, struct dentry *parent
 
 	ti = get_tracefs(inode);
 	ti->flags |= TRACEFS_EVENT_INODE;
+	/* Only directories have ti->private set to an ei, not files */
+	ti->private = ei;
 
 	inc_nlink(inode);
 	d_instantiate(dentry, inode);
@@ -515,7 +517,6 @@ create_file_dentry(struct eventfs_inode *ei, int idx,
 static void eventfs_post_create_dir(struct eventfs_inode *ei)
 {
 	struct eventfs_inode *ei_child;
-	struct tracefs_inode *ti;
 
 	lockdep_assert_held(&eventfs_mutex);
 
@@ -525,9 +526,6 @@ static void eventfs_post_create_dir(struct eventfs_inode *ei)
 				 srcu_read_lock_held(&eventfs_srcu)) {
 		ei_child->d_parent = ei->dentry;
 	}
-
-	ti = get_tracefs(ei->dentry->d_inode);
-	ti->private = ei;
 }
 
 /**
-- 
2.43.0