linux-kernel - [2.6 patch] include/linux/nfsd/nfsfh.h:fh_unlock(): change an error to a BUG

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Date:	Sun, 12 Nov 2006 18:48:31 +0100
From:	Adrian Bunk <bunk@...sta.de>
To:	Trond Myklebust <trond.myklebust@....uio.no>
Cc:	neilb@....unsw.edu.au, nfs@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org
Subject: [2.6 patch] include/linux/nfsd/nfsfh.h:fh_unlock(): change an error to a BUG_ON()

On Sun, Nov 12, 2006 at 10:58:47AM -0500, Trond Myklebust wrote:
> On Sun, 2006-11-12 at 14:17 +0100, Adrian Bunk wrote:
> > dereference
> > Reply-To: 
> > Fcc: =sent-mail
> > 
> > When we know fhp->fh_dentry is NULL, a code path where it's being 
> > dereferenced isn't a good choice.
> > 
> > Spotted by the coverity checker.
> > 
> > Signed-off-by: Adrian Bunk <bunk@...sta.de>
> > 
> > --- linux-2.6/include/linux/nfsd/nfsfh.h.old	2006-11-12 14:13:34.000000000 +0100
> > +++ linux-2.6/include/linux/nfsd/nfsfh.h	2006-11-12 14:13:49.000000000 +0100
> > @@ -330,8 +330,7 @@ fh_unlock(struct svc_fh *fhp)
> >  {
> >  	if (!fhp->fh_dentry)
> >  		printk(KERN_ERR "fh_unlock: fh not verified!\n");
> > -
> > -	if (fhp->fh_locked) {
> > +	else if (fhp->fh_locked) {
> >  		fill_post_wcc(fhp);
> >  		mutex_unlock(&fhp->fh_dentry->d_inode->i_mutex);
> >  		fhp->fh_locked = 0;
> > 
> 
> This issue has come up on lkml before. Please just convert that check
> for fhp->fh_dentry into a BUG_ON().

Patch below.

> Trond

cu
Adrian


<--  snip  -->


!fhp->fh_dentry is a condition that mustn't ever happen (and we might 
run into additional trouble later).

Signed-off-by: Adrian Bunk <bunk@...sta.de>

--- linux-2.6/include/linux/nfsd/nfsfh.h.old	2006-11-12 18:37:43.000000000 +0100
+++ linux-2.6/include/linux/nfsd/nfsfh.h	2006-11-12 18:38:03.000000000 +0100
@@ -328,8 +328,7 @@
 static inline void
 fh_unlock(struct svc_fh *fhp)
 {
-	if (!fhp->fh_dentry)
-		printk(KERN_ERR "fh_unlock: fh not verified!\n");
+	BUG_ON(!fhp->fh_dentry);
 
 	if (fhp->fh_locked) {
 		fill_post_wcc(fhp);

-
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