Adjust the relayd protocol on version check

[lttng-tools.git] / src / common / relayd / relayd.c

diff --git a/src/common/relayd/relayd.c b/src/common/relayd/relayd.c
index 9e10c83e02f7ec583bff72cd5b6d70b42870dca1..da54939f9a28153e4ae343d281ec1352e07b8ef9 100644 (file)
--- a/src/common/relayd/relayd.c
+++ b/src/common/relayd/relayd.c
@@ -212,11 +212,13 @@ error:
 
 /*
  * Check version numbers on the relayd.
+ * If major versions are compatible, we assign minor_to_use to the
+ * minor version of the procotol we are going to use for this session.
  *
  * Return 0 if compatible else negative value.
  */
 int relayd_version_check(struct lttcomm_sock *sock, uint32_t major,
-               uint32_t minor)
+               uint32_t minor, uint32_t *minor_to_use)
 {
        int ret;
        struct lttcomm_relayd_version msg;
@@ -251,15 +253,12 @@ int relayd_version_check(struct lttcomm_sock *sock, uint32_t major,
         * communication is not possible. Only major version equal can talk to each
         * other. If the minor version differs, the lowest version is used by both
         * sides.
-        *
-        * For now, before 2.1.0 stable release, we don't have to check the minor
-        * because this new mechanism with the relayd will only be available with
-        * 2.1 and NOT 2.0.x.
         */
-       if (msg.major == major) {
-               /* Compatible */
-               ret = 0;
-               DBG2("Relayd version is compatible");
+       if (msg.major != major) {
+               /* Not compatible */
+               ret = -1;
+               DBG2("Relayd version is NOT compatible. Relayd version %u != %u (us)",
+                               msg.major, major);
                goto error;
        }
 
@@ -270,11 +269,16 @@ int relayd_version_check(struct lttcomm_sock *sock, uint32_t major,
         * version is higher, it will adapt to our version so we can continue to
         * use the latest relayd communication data structure.
         */
+       if (minor <= msg.minor) {
+               *minor_to_use = minor;
+       } else {
+               *minor_to_use = msg.minor;
+       }
 
-       /* Version number not compatible */
-       DBG2("Relayd version is NOT compatible. Relayd version %u != %u (us)",
-                       msg.major, major);
-       ret = -1;
+       /* Version number compatible */
+       DBG2("Relayd version is compatible, using protocol version %u.%u",
+                       major, *minor_to_use);
+       ret = 0;
 
 error:
        return ret;