ovs-router: Fix locking in ovs_router_rule_add().

ovs_router_rule_add() is annotated with OVS_REQUIRES(mutex) but its
external caller rule_handle_msg() in route-table.c does not hold the
mutex. This could lead to data races on the rules pvector.

Fix this by changing the annotation to OVS_EXCLUDED(mutex) and
acquiring the mutex inside ovs_router_rule_add() around the call to
the internal ovs_router_rule_add__() function.

Fixes: dc14e92 ("route-table: Introduce multi-table route lookup.")
Signed-off-by: Matteo Perin <matteo.perin@canonical.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

Author: matperin

lib/ovs-router.c

@@ -1339,11 +1339,13 @@ void
 ovs_router_rule_add(uint32_t prio, bool invert, bool user, uint8_t src_len,
                     const struct in6_addr *from, uint32_t lookup_table,
                     bool ipv4)
-    OVS_REQUIRES(mutex)
+    OVS_EXCLUDED(mutex)
 {
     if (use_system_routing_table) {
+        ovs_mutex_lock(&mutex);
         ovs_router_rule_add__(prio, invert, user, src_len, from,
                               lookup_table, ipv4);
+        ovs_mutex_unlock(&mutex);
     }
 }