svcrpc: introduce init_svc_cred

Common helper to zero out fields of the svc_cred.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

include/linux/sunrpc/svcauth.h

@@ -25,6 +25,13 @@ struct svc_cred {
 	char			*cr_principal; /* for gss */
 };
 
+static inline void init_svc_cred(struct svc_cred *cred)
+{
+	cred->cr_group_info = NULL;
+	cred->cr_principal = NULL;
+	cred->cr_gss_mech = NULL;
+}
+
 static inline void free_svc_cred(struct svc_cred *cred)
 {
 	if (cred->cr_group_info)

net/sunrpc/auth_gss/svcauth_gss.c

@@ -377,8 +377,7 @@ rsc_init(struct cache_head *cnew, struct cache_head *ctmp)
 	new->handle.data = tmp->handle.data;
 	tmp->handle.data = NULL;
 	new->mechctx = NULL;
-	new->cred.cr_group_info = NULL;
-	new->cred.cr_principal = NULL;
+	init_svc_cred(&new->cred);
 }
 
 static void
@@ -392,9 +391,8 @@ update_rsc(struct cache_head *cnew, struct cache_head *ctmp)
 	memset(&new->seqdata, 0, sizeof(new->seqdata));
 	spin_lock_init(&new->seqdata.sd_lock);
 	new->cred = tmp->cred;
-	tmp->cred.cr_group_info = NULL;
 	new->cred.cr_principal = tmp->cred.cr_principal;
-	tmp->cred.cr_principal = NULL;
+	init_svc_cred(&tmp->cred);
 }
 
 static struct cache_head *