Re: [PATCH] proc: proc_get_inode should de_put when inode already initialized

Andrew Morton
2009-02-23T23:26:38Z

On Mon, 23 Feb 2009 22:21:55 +0100
Krzysztof Sachanowicz <analyzer1@gmail.com> wrote:

> de_get is called before every proc_get_inode, but corresponding de_put is
> called only when dropping last reference to an inode. This might cause
> something like
> remove_proc_entry: /proc/stats busy, count=14496
> to be printed to the syslog.
>
> The fix is to call de_put in case of an already initialized inode in
> proc_get_inode.
>
> Signed-off-by: Krzysztof Sachanowicz <analyzer1@gmail.com>
> Tested-by: Marcin Pilipczuk <marcin.pilipczuk@gmail.com>
> ---
> --- linux-2.6.29-rc6.orig/fs/proc/inode.c 2009-02-23 20:43:32.000000000 +0100
> +++ linux-2.6.29-rc6/fs/proc/inode.c 2009-02-23 20:46:37.000000000 +0100
> @@ -485,8 +485,10 @@ struct inode *proc_get_inode(struct supe
> }
> }
> unlock_new_inode(inode);
> - } else
> + } else {
> module_put(de->owner);
> + de_put(de);
> + }
> return inode;
>
> out_ino:

This code area looks quite different in linux-next, although the
changes there are removing proc_dir_entry.owner altogether and aren't
obviously targetted at fixing this bug.

Also...

It's unpleasing to have the de_get() inside the caller and the de_put()
inside the callee - it is better to have them both happening at the
same level. If it is the case that "de_get is called before every
proc_get_inode", then perhaps that operation should simply be moved
into proc_get_inode().