SUNRPC: Fix up svc_unregister()

With the new rpcbind code, a PMAP_UNSET will not have any effect on
services registered via rpcbind v3 or v4.

Implement a version of svc_unregister() that uses an RPCB_UNSET with
an empty netid string to make sure we have cleared *all* entries for
a kernel RPC service when shutting down, or before starting a fresh
instance of the service.

Use the new version only when CONFIG_SUNRPC_REGISTER_V4 is enabled;
otherwise, the legacy PMAP version is used to ensure complete
backwards-compatibility with the Linux portmapper daemon.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 38 insertions, 20 deletions

diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index b8d2fcd0f715..54c98d876847 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -896,31 +896,51 @@ int svc_register(const struct svc_serv *serv, const unsigned short proto,
         return error;
 }
 
+#ifdef CONFIG_SUNRPC_REGISTER_V4
+
+static void __svc_unregister(const u32 program, const u32 version,
+                             const char *progname)
+{
+        struct sockaddr_in6 sin6 = {
+                .sin6_family            = AF_INET6,
+                .sin6_addr              = IN6ADDR_ANY_INIT,
+                .sin6_port              = 0,
+        };
+        int error;
+
+        error = rpcb_v4_register(program, version,
+                                (struct sockaddr *)&sin6, "");
+        dprintk("svc: %s(%sv%u), error %d\n",
+                        __func__, progname, version, error);
+}
+
+#else   /* CONFIG_SUNRPC_REGISTER_V4 */
+
+static void __svc_unregister(const u32 program, const u32 version,
+                             const char *progname)
+{
+        int error;
+
+        error = rpcb_register(program, version, 0, 0);
+        dprintk("svc: %s(%sv%u), error %d\n",
+                        __func__, progname, version, error);
+}
+
+#endif  /* CONFIG_SUNRPC_REGISTER_V4 */
+
 /*
- * All transport protocols and ports for this service are removed
- * from the local rpcbind database if the service is not hidden.
- *
- * The result of unregistration is reported via dprintk for those
- * who want verification of the result, but is otherwise not
- * important.
+ * All netids, bind addresses and ports registered for [program, version]
+ * are removed from the local rpcbind database (if the service is not
+ * hidden) to make way for a new instance of the service.
  *
- * The local rpcbind daemon listens on either only IPv6 or only
- * IPv4.  The kernel can't tell how it's configured.  However,
- * AF_INET addresses are mapped to AF_INET6 in IPv6-only config-
- * urations, so even an unregistration request on AF_INET will
- * get to a local rpcbind daemon listening only on AF_INET6.  So
- * we always unregister via AF_INET.
- *
- * At this point we don't need rpcbind version 4 for unregis-
- * tration:  A v2 UNSET request will clear all transports (netids),
- * addresses, and address families for [program, version].
+ * The result of unregistration is reported via dprintk for those who want
+ * verification of the result, but is otherwise not important.
  */
 static void svc_unregister(const struct svc_serv *serv)
 {
         struct svc_program *progp;
         unsigned long flags;
         unsigned int i;
-        int error;
 
         clear_thread_flag(TIF_SIGPENDING);
 
@@ -931,9 +951,7 @@ static void svc_unregister(const struct svc_serv *serv)
                         if (progp->pg_vers[i]->vs_hidden)
                                 continue;
 
-                        error = rpcb_register(progp->pg_prog, i, 0, 0);
-                        dprintk("svc: svc_unregister(%sv%u), error %d\n",
-                                        progp->pg_name, i, error);
+                        __svc_unregister(progp->pg_prog, i, progp->pg_name);
                 }
         }