[PATCH v3 02/29] lockd: Use xdrgen XDR functions for the NLMv4 NULL procedure

[Chuck Lever <cel@kernel.org>]

From: Chuck Lever <chuck.lever@oracle.com>

Hand-written XDR encoders and decoders are difficult to maintain
and can inadvertently diverge from protocol specifications. By
migrating to xdrgen-generated code, we improve type safety and
ensure the implementation exactly matches the NLM version 4
protocol specification.

This patch begins the migration by converting the NULL procedure
to use nlm4_svc_decode_void and nlm4_svc_encode_void generated
from Documentation/sunrpc/xdr/nlm4.x. The NULL procedure is
straightforward as it has no arguments or results, making it an
ideal starting point for this series.

The pc_xdrressize field is set to XDR_void (zero) to reflect
that this procedure returns no XDR-encoded data. The argzero
field is also set to zero since xdrgen decoders reliably
initialize all decoded values.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/lockd/svc4proc.c | 40 ++++++++++++++++++++++++++++------------
 1 file changed, 28 insertions(+), 12 deletions(-)

diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
index c99f192bce77..4fcd66beb4df 100644
--- a/fs/lockd/svc4proc.c
+++ b/fs/lockd/svc4proc.c
@@ -13,7 +13,17 @@
 #include <linux/sunrpc/svc_xprt.h>
 
 #include "lockd.h"
+
+/*
+ * xdr.h defines SM_MAXSTRLEN and SM_PRIV_SIZE as macros.
+ * nlm4xdr_gen.h defines them as enum constants. Undefine the
+ * macros to allow the xdrgen enum definitions to be used.
+ */
+#undef SM_MAXSTRLEN
+#undef SM_PRIV_SIZE
+
 #include "share.h"
+#include "nlm4xdr_gen.h"
 #include "xdr4.h"
 
 #define NLMDBG_FACILITY		NLMDBG_CLIENT
@@ -92,13 +102,19 @@ nlm4svc_retrieve_args(struct svc_rqst *rqstp, struct nlm_args *argp,
 	}
 }
 
-/*
- * NULL: Test for presence of service
+/**
+ * nlm4svc_proc_null - NULL: Test for presence of service
+ * @rqstp: RPC transaction context
+ *
+ * Returns:
+ *   %rpc_success:		RPC executed successfully
+ *
+ * RPC synopsis:
+ *   void NLMPROC4_NULL(void) = 0;
  */
 static __be32
 nlm4svc_proc_null(struct svc_rqst *rqstp)
 {
-	dprintk("lockd: NULL          called\n");
 	return rpc_success;
 }
 
@@ -531,15 +547,15 @@ struct nlm_void			{ int dummy; };
 #define	Rg	4					/* range (offset + length) */
 
 static const struct svc_procedure nlm4svc_procedures[24] = {
-	[NLMPROC_NULL] = {
-		.pc_func = nlm4svc_proc_null,
-		.pc_decode = nlm4svc_decode_void,
-		.pc_encode = nlm4svc_encode_void,
-		.pc_argsize = sizeof(struct nlm_void),
-		.pc_argzero = sizeof(struct nlm_void),
-		.pc_ressize = sizeof(struct nlm_void),
-		.pc_xdrressize = St,
-		.pc_name = "NULL",
+	[NLMPROC4_NULL] = {
+		.pc_func	= nlm4svc_proc_null,
+		.pc_decode	= nlm4_svc_decode_void,
+		.pc_encode	= nlm4_svc_encode_void,
+		.pc_argsize	= XDR_void,
+		.pc_argzero	= 0,
+		.pc_ressize	= 0,
+		.pc_xdrressize	= XDR_void,
+		.pc_name	= "NULL",
 	},
 	[NLMPROC_TEST] = {
 		.pc_func = nlm4svc_proc_test,
-- 
2.53.0