SUNRPC: Hoist init_decode out of svc_authenticate()

Now that each ->accept method has been converted to use xdr_stream,
the svcxdr_init_decode() calls can be hoisted back up into the
generic RPC server code.

The dprintk in svc_authenticate() is removed, since
trace_svc_authenticate() reports the same information.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

net/sunrpc/auth_gss/svcauth_gss.c

@@ -1619,8 +1619,6 @@ svcauth_gss_accept(struct svc_rqst *rqstp)
 	int		ret;
 	struct sunrpc_net *sn = net_generic(SVC_NET(rqstp), sunrpc_net_id);
 
-	svcxdr_init_decode(rqstp);
-
 	rqstp->rq_auth_stat = rpc_autherr_badcred;
 	if (!svcdata)
 		svcdata = kmalloc(sizeof(*svcdata), GFP_KERNEL);

net/sunrpc/svc.c

@@ -1276,6 +1276,7 @@ svc_process_common(struct svc_rqst *rqstp, struct kvec *argv, struct kvec *resv)
 	 * We do this before anything else in order to get a decent
 	 * auth verifier.
 	 */
+	svcxdr_init_decode(rqstp);
 	auth_res = svc_authenticate(rqstp);
 	/* Also give the program a chance to reject this call: */
 	if (auth_res == SVC_OK && progp)

net/sunrpc/svcauth.c

@@ -63,14 +63,17 @@ svc_put_auth_ops(struct auth_ops *aops)
 int
 svc_authenticate(struct svc_rqst *rqstp)
 {
-	rpc_authflavor_t	flavor;
 	struct auth_ops *aops;
+	u32 flavor;
 
 	rqstp->rq_auth_stat = rpc_auth_ok;
 
-	flavor = svc_getnl(&rqstp->rq_arg.head[0]);
-
-	dprintk("svc: svc_authenticate (%d)\n", flavor);
+	/*
+	 * Decode the Call credential's flavor field. The credential's
+	 * body field is decoded in the chosen ->accept method below.
+	 */
+	if (xdr_stream_decode_u32(&rqstp->rq_arg_stream, &flavor) < 0)
+		return SVC_GARBAGE;
 
 	aops = svc_get_auth_ops(flavor);
 	if (aops == NULL) {

net/sunrpc/svcauth_unix.c

@@ -750,8 +750,6 @@ svcauth_null_accept(struct svc_rqst *rqstp)
 	u32 flavor, len;
 	void *body;
 
-	svcxdr_init_decode(rqstp);
-
 	/* Length of Call's credential body field: */
 	if (xdr_stream_decode_u32(xdr, &len) < 0)
 		return SVC_GARBAGE;
@@ -828,8 +826,6 @@ svcauth_tls_accept(struct svc_rqst *rqstp)
 	u32 flavor, len;
 	void *body;
 
-	svcxdr_init_decode(rqstp);
-
 	/* Length of Call's credential body field: */
 	if (xdr_stream_decode_u32(xdr, &len) < 0)
 		return SVC_GARBAGE;
@@ -905,8 +901,6 @@ svcauth_unix_accept(struct svc_rqst *rqstp)
 	void *body;
 	__be32 *p;
 
-	svcxdr_init_decode(rqstp);
-
 	/*
 	 * This implementation ignores the length of the Call's
 	 * credential body field and the timestamp and machinename