rcu: convert uses of rcu_assign_pointer(x, NULL) to RCU_INIT_POINTER

When assigning a NULL value to an RCU protected pointer, no barrier
is needed. The rcu_assign_pointer, used to handle that but will soon
change to not handle the special case.

Convert all rcu_assign_pointer of NULL value.

//smpl
@@ expression P; @@

- rcu_assign_pointer(P, NULL)
+ RCU_INIT_POINTER(P, NULL)

// </smpl>

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index 364eb45..d413275 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -122,7 +122,7 @@
 	if (!test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags))
 		return;
 	gss_get_ctx(ctx);
-	rcu_assign_pointer(gss_cred->gc_ctx, ctx);
+	RCU_INIT_POINTER(gss_cred->gc_ctx, ctx);
 	set_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
 	smp_mb__before_clear_bit();
 	clear_bit(RPCAUTH_CRED_NEW, &cred->cr_flags);
@@ -970,7 +970,7 @@
 	struct gss_auth *gss_auth = container_of(cred->cr_auth, struct gss_auth, rpc_auth);
 	struct gss_cl_ctx *ctx = gss_cred->gc_ctx;
 
-	rcu_assign_pointer(gss_cred->gc_ctx, NULL);
+	RCU_INIT_POINTER(gss_cred->gc_ctx, NULL);
 	call_rcu(&cred->cr_rcu, gss_free_cred_callback);
 	if (ctx)
 		gss_put_ctx(ctx);