[PATCH] knfsd: svcrpc: WARN() instead of returning an error from svc_take_page

Every caller of svc_take_page ignores its return value and assumes it
succeeded.  So just WARN() instead of returning an ignored error.  This would
have saved some time debugging a recent nfsd4 problem.

If there are still failure cases here, then the result is probably that we
overwrite an earlier part of the reply while xdr-encoding.

While the corrupted reply is a nasty bug, it would be worse to panic here and
create the possibility of a remote DOS; hence WARN() instead of BUG().
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Ingo Oeser <ioe-lkml@rameria.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/sunrpc/svc.h

@@ -197,15 +197,16 @@ svc_take_res_page(struct svc_rqst *rqstp)
 	return rqstp->rq_respages[rqstp->rq_resused++];
 }
 
-static inline int svc_take_page(struct svc_rqst *rqstp)
+static inline void svc_take_page(struct svc_rqst *rqstp)
 {
-	if (rqstp->rq_arghi <= rqstp->rq_argused)
-		return -ENOMEM;
+	if (rqstp->rq_arghi <= rqstp->rq_argused) {
+		WARN_ON(1);
+		return;
+	}
 	rqstp->rq_arghi--;
 	rqstp->rq_respages[rqstp->rq_resused] =
 		rqstp->rq_argpages[rqstp->rq_arghi];
 	rqstp->rq_resused++;
-	return 0;
 }
 
 static inline void svc_pushback_allpages(struct svc_rqst *rqstp)