Re: [PATCH 5/5] efivarfs: efivarfs_fill_super() ensure we clean up correctly on error

Andy Whitcroft
2012-10-11T16:06:43Z

On Thu, Oct 11, 2012 at 10:04:28PM +0800, Jeremy Kerr wrote:
> Hi Andy,
>
> >@@ -969,16 +970,18 @@
> > return -ENOMEM;
> >
> > list_for_each_entry_safe(entry, n, &efivars->list, list) {
> >- struct inode *inode;
> > struct dentry *dentry, *root = efivarfs_sb->s_root;
> >- char *name;
> > unsigned long size = 0;
> > int len, i;
> >
> >+ inode = NULL;
> >+
> > len = utf16_strlen(entry->var.VariableName);
> >
> > /* GUID plus trailing NULL */
> > name = kmalloc(len + 38, GFP_ATOMIC);
> >+ if (!name)
> >+ goto fail;
> >
> > for (i = 0; i < len; i++)
> > name[i] = entry->var.VariableName[i] & 0xFF;
> >@@ -991,7 +994,13 @@
> >
> > inode = efivarfs_get_inode(efivarfs_sb, root->d_inode,
> > S_IFREG | 0644, 0);
> >+ if (!inode)
> >+ goto fail_name;
> >+
> > dentry = d_alloc_name(root, name);
> >+ if (!dentry)
> >+ goto fail_inode;
> >+
> > /* copied by the above to local storage in the dentry. */
> > kfree(name);
>
> If we break out of the loop on the second (and onwards) iteration,
> won't we still have the other inodes and dentries remaining
> allocated?

As we calling this from the mount_single() wrapper:

return mount_single(fs_type, flags, data, efivarfs_fill_super);

which does this:

struct dentry *mount_single(struct file_system_type *fs_type,
int flags, void *data,
int (*fill_super)(struct super_block *, void *, int))
{
[...]
error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
if (error) {
deactivate_locked_super(s);
return ERR_PTR(error);
}
[...]

I am expecting us to get called back via deactivate_locked_super(),
which calls sb->kill_sb() which is:

static void efivarfs_kill_sb(struct super_block *sb)
{
kill_litter_super(sb);
efivarfs_sb = NULL;
}

Which I believe will clean them up.

-apw