First, thank you Akinobu for discovering the bug.
On Mon, Mar 05, 2007 at 12:16:59AM +0900, Akinobu Mita wrote:
> On Sun, Mar 04, 2007 at 03:10:19PM +0100, Arnd Bergmann wrote:
> > This should be changed to jump to a new exit point, before the mutex_unlock
> > at the end of the function. Having multiple places in the function that
> > release the same lock easily leads to the kind of bug you are fixing here.
>
> Agreed. Please see the patch below (untested).
Jumping isn't always the solution. The new patch, while better
than the first, still calls mutex_unlock() in two places. The following
patch keeps it all in one code path, and keeps all dentry modification
underneath a single mutex_lock()/unlock() pair. What do you think? I'm
building it to test as we speak.
Joel
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index 1814ba4..489c265 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -1142,25 +1142,22 @@ int configfs_register_subsystem(struct
configfs_subsystem *subsys)
err = -ENOMEM;
dentry = d_alloc(configfs_sb->s_root, &name);
- if (!dentry)
- goto out_release;
-
- d_add(dentry, NULL);
+ if (dentry) {
+ d_add(dentry, NULL);
- err = configfs_attach_group(sd->s_element, &group->cg_item,
- dentry);
- if (!err)
- dentry = NULL;
- else
- d_delete(dentry);
+ err = configfs_attach_group(sd->s_element, &group->cg_item,
+ dentry);
+ if (err) {
+ d_delete(dentry);
+ dput(dentry);
+ }
+ }
mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
- if (dentry) {
- dput(dentry);
-out_release:
- unlink_group(group);
- configfs_release_fs();
+ if (err) {
+ unlink_group(group);
+ configfs_release_fs();
}
return err;
--
"Nobody loves me,
Nobody seems to care.
Troubles and worries, people,
You know I've had my share."
Joel Becker
Principal Software Developer
Oracle
E-mail: [EMAIL PROTECTED]
Phone: (650) 506-8127
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