Re: [PATCH] sysfs: move assignment to be under lock in sysfs_remove_dir()

[ebiederm@xmission.com (Eric W. Biederman)]

Greg KH <gregkh@linuxfoundation.org> writes:

> From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> Linus noticed that the assignment of sd isn't protected by the lock in
> sysfs_remove_dir(), so move the assignment of the variable under the
> lock to be safe.
>
> Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>

> ---
>
> Tejun, any objection to this patch?  You consolidated the locks back in
> 2007 on this function, and nothing has changed there since then, so odds
> are it's not a problem, but nice to be safe, right?
>
>  fs/sysfs/dir.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
> index eab59de4..2609f934 100644
> --- a/fs/sysfs/dir.c
> +++ b/fs/sysfs/dir.c
> @@ -856,9 +856,10 @@ void sysfs_remove(struct sysfs_dirent *sd)
>   */
>  void sysfs_remove_dir(struct kobject *kobj)
>  {
> -	struct sysfs_dirent *sd = kobj->sd;
> +	struct sysfs_dirent *sd;
>  
>  	spin_lock(&sysfs_assoc_lock);
> +	sd = kobj->sd;
>  	kobj->sd = NULL;
>  	spin_unlock(&sysfs_assoc_lock);
>