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eventfs: Add WARN_ON_ONCE() to checks in eventfs_root_lookup()

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There's a couple of if statements in eventfs_root_lookup() that should
never be true. Instead of removing them, add WARN_ON_ONCE() around them.

  One is a tracefs_inode not being for eventfs.

  The other is a child being freed but still on the parent's children
  list. When a child is freed, it is removed from the list under the
  same mutex that is held during the iteration.

Link: https://lore.kernel.org/linux-trace-kernel/20240201002719.GS2087318@ZenIV/
Link: https://lore.kernel.org/linux-trace-kernel/20240201123346.724afa46@gandalf.local.home

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ajay Kaher <ajay.kaher@broadcom.com>
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Google) 2024-02-01 12:33:46 -05:00
parent 63bd30f249
commit 04204cd9b0
1 changed files with 3 additions and 2 deletions
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5
fs/tracefs/event_inode.c
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@ -483,7 +483,7 @@ static struct dentry *eventfs_root_lookup(struct inode *dir,
struct dentry *result = NULL;
ti = get_tracefs(dir);
if (!(ti->flags & TRACEFS_EVENT_INODE))
if (WARN_ON_ONCE(!(ti->flags & TRACEFS_EVENT_INODE)))
return ERR_PTR(-EIO);
mutex_lock(&eventfs_mutex);
@ -495,7 +495,8 @@ static struct dentry *eventfs_root_lookup(struct inode *dir,
list_for_each_entry(ei_child, &ei->children, list) {
if (strcmp(ei_child->name, name) != 0)
continue;
if (ei_child->is_freed)
/* A child is freed and removed from the list at the same time */
if (WARN_ON_ONCE(ei_child->is_freed))
goto out;
result = lookup_dir_entry(dentry, ei, ei_child);
goto out;