Re: [PATCH] sysfs: kill an extra put in sysfs_create_link() failure path

Miles Lane
2007-07-18T14:29:31Z

On 7/18/07, Tejun Heo <htejun@gmail.com> wrote:
> There is a subtle bug in sysfs_create_link() failure path. When
> symlink creation fails because there's already a node with the same
> name, the target sysfs_dirent is put twice - once by failure path of
> sysfs_create_link() and once more when the symlink is released.
>
> Fix it by making only the symlink node responsible for putting
> target_sd.
>
> Signed-off-by: Tejun Heo <htejun@gmail.com>
> ---
> Gabriel, Miles, please verify this fixes your problem. Thanks.
>
> fs/sysfs/symlink.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
> index 2f86e04..d056e96 100644
> --- a/fs/sysfs/symlink.c
> +++ b/fs/sysfs/symlink.c
> @@ -86,7 +86,9 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
> sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
> if (!sd)
> goto out_put;
> +
> sd->s_elem.symlink.target_sd = target_sd;
> + target_sd = NULL; /* reference is now owned by the symlink */
>
> sysfs_addrm_start(&acxt, parent_sd);
>
> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
>

Great! I tested with both patches applied to 2.6.22-rc6-mm1 and was
able to remove ipw2200 without triggering the BUG.

Thanks,
Miles