devlink: Protect devlink port list traversal

Cited patch in fixes tag misses to protect port list traversal
while traversing per port reporter list.

Protect it using devlink instance lock.

Fixes: f4f54166 ("devlink: Implement devlink health reporters on per-port basis")
Signed-off-by: NParav Pandit <parav@nvidia.com>
Reviewed-by: NJiri Pirko <jiri@nvidia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/devlink.c

@@ -5895,6 +5895,7 @@ devlink_nl_cmd_health_reporter_get_dumpit(struct sk_buff *msg,
 	list_for_each_entry(devlink, &devlink_list, list) {
 		if (!net_eq(devlink_net(devlink), sock_net(msg->sk)))
 			continue;
+		mutex_lock(&devlink->lock);
 		list_for_each_entry(port, &devlink->port_list, list) {
 			mutex_lock(&port->reporters_lock);
 			list_for_each_entry(reporter, &port->reporter_list, list) {
@@ -5909,12 +5910,14 @@ devlink_nl_cmd_health_reporter_get_dumpit(struct sk_buff *msg,
 								      NLM_F_MULTI);
 				if (err) {
 					mutex_unlock(&port->reporters_lock);
+					mutex_unlock(&devlink->lock);
 					goto out;
 				}
 				idx++;
 			}
 			mutex_unlock(&port->reporters_lock);
 		}
+		mutex_unlock(&devlink->lock);
 	}
 out:
 	mutex_unlock(&devlink_mutex);