lib: introduce a read-write lock for northbound configurations

The upcoming gRPC-based northbound plugin will run on a separate
pthread, and it will need to have access to the running configuration
global variable.  Introduce a rw-lock to control concurrent access
to the running configuration. Add the lock inside the "nb_config"
structure so that it can be used to protect candidate configurations
as well (this might be necessary depending on the threading scheme
of future northbound plugins).

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>

1 files changed, 11 insertions, 8 deletions

diff --git a/lib/if.c b/lib/if.c
index 86b850c059..38f3f45ed1 100644
--- a/lib/if.c
+++ b/lib/if.c
@@ -187,18 +187,21 @@ void if_update_to_new_vrf(struct interface *ifp, vrf_id_t vrf_id)
 	if (yang_module_find("frr-interface")) {
 		struct lyd_node *if_dnode;
 
-		if_dnode = yang_dnode_get(
-			running_config->dnode,
-			"/frr-interface:lib/interface[name='%s'][vrf='%s']/vrf",
-			ifp->name, old_vrf->name);
-		if (if_dnode) {
-			yang_dnode_change_leaf(if_dnode, vrf->name);
-			running_config->version++;
+		pthread_rwlock_wrlock(&running_config->lock);
+		{
+			if_dnode = yang_dnode_get(
+				running_config->dnode,
+				"/frr-interface:lib/interface[name='%s'][vrf='%s']/vrf",
+				ifp->name, old_vrf->name);
+			if (if_dnode) {
+				yang_dnode_change_leaf(if_dnode, vrf->name);
+				running_config->version++;
+			}
 		}
+		pthread_rwlock_unlock(&running_config->lock);
 	}
 }
 
-
 /* Delete interface structure. */
 void if_delete_retain(struct interface *ifp)
 {