Removing the rte_modify API

For BGP LLGR purposes, there was an API allowing a protocol to directly
modify their stale routes in table before flushing them. This API was
called by the table prune routine which violates the future locking
requirements.

Instead of this, BGP now requests a special route export and reimports
these routes into the table, allowing for asynchronous execution without
locking the table on export.

1 files changed, 51 insertions, 3 deletions

diff --git a/proto/bgp/bgp.c b/proto/bgp/bgp.c
index d9008b9a..fb8fa529 100644
--- a/proto/bgp/bgp.c
+++ b/proto/bgp/bgp.c
@@ -139,6 +139,9 @@ static void bgp_update_bfd(struct bgp_proto *p, const struct bfd_options *bfd);
 static int bgp_incoming_connection(sock *sk, uint dummy UNUSED);
 static void bgp_listen_sock_err(sock *sk UNUSED, int err);
 
+static void bgp_graceful_restart_feed(struct bgp_channel *c);
+
+
 /**
  * bgp_open - open a BGP instance
  * @p: BGP instance
@@ -770,7 +773,7 @@ bgp_handle_graceful_restart(struct bgp_proto *p)
 
       case BGP_GRS_LLGR:
 	rt_refresh_begin(&c->c.in_req);
-	rt_modify_stale(c->c.table, &c->c.in_req);
+	bgp_graceful_restart_feed(c);
 	break;
       }
     }
@@ -796,6 +799,52 @@ bgp_handle_graceful_restart(struct bgp_proto *p)
   tm_start(p->gr_timer, p->conn->remote_caps->gr_time S);
 }
 
+static void
+bgp_graceful_restart_feed_done(struct rt_export_request *req)
+{
+  req->hook = NULL;
+}
+
+static void
+bgp_graceful_restart_feed_dump_req(struct rt_export_request *req)
+{
+  struct bgp_channel *c = SKIP_BACK(struct bgp_channel, stale_feed, req);
+  debug("  BGP-GR %s.%s export request %p\n", c->c.proto->name, c->c.name, req);
+}
+
+static void
+bgp_graceful_restart_feed_log_state_change(struct rt_export_request *req, u8 state)
+{
+  struct bgp_channel *c = SKIP_BACK(struct bgp_channel, stale_feed, req);
+  struct bgp_proto *p = (void *) c->c.proto;
+  BGP_TRACE(D_EVENTS, "Long-lived graceful restart export state changed to %s", rt_export_state_name(state));
+
+  if (state == TES_READY)
+    rt_stop_export(req, bgp_graceful_restart_feed_done);
+}
+
+static void
+bgp_graceful_restart_drop_export(struct rt_export_request *req UNUSED, const net_addr *n UNUSED, struct rt_pending_export *rpe UNUSED)
+{ /* Nothing to do */ }
+
+static void
+bgp_graceful_restart_feed(struct bgp_channel *c)
+{
+  c->stale_feed = (struct rt_export_request) {
+    .name = "BGP-GR",
+    .trace_routes = c->c.debug | c->c.proto->debug,
+    .dump_req = bgp_graceful_restart_feed_dump_req,
+    .log_state_change = bgp_graceful_restart_feed_log_state_change,
+    .export_bulk = bgp_rte_modify_stale,
+    .export_one = bgp_graceful_restart_drop_export,
+  };
+
+  rt_request_export(&c->c.table->exporter, &c->stale_feed);
+}
+
+
+
+
 /**
  * bgp_graceful_restart_done - finish active BGP graceful restart
  * @c: BGP channel
@@ -861,7 +910,7 @@ bgp_graceful_restart_timeout(timer *t)
       /* Channel is in GR, and supports LLGR -> start LLGR */
       c->gr_active = BGP_GRS_LLGR;
       tm_start(c->stale_timer, c->stale_time S);
-      rt_modify_stale(c->c.table, &c->c.in_req);
+      bgp_graceful_restart_feed(c);
     }
   }
   else
@@ -1672,7 +1721,6 @@ bgp_init(struct proto_config *CF)
   P->rte_better = bgp_rte_better;
   P->rte_mergable = bgp_rte_mergable;
   P->rte_recalculate = cf->deterministic_med ? bgp_rte_recalculate : NULL;
-  P->rte_modify = bgp_rte_modify_stale;
   P->rte_igp_metric = bgp_rte_igp_metric;
 
   p->cf = cf;