Fix: add provider ABI compatibility check

[lttng-ust.git] / liblttng-ust / lttng-probes.c

diff --git a/liblttng-ust/lttng-probes.c b/liblttng-ust/lttng-probes.c
index f028ccab8cadd967971cb3f673b883f622b03f7e..433171cfb04635c424394a9e2c292f82a70a8ae4 100644 (file)
--- a/liblttng-ust/lttng-probes.c
+++ b/liblttng-ust/lttng-probes.c
@@ -160,10 +160,47 @@ const struct lttng_probe_desc *find_provider(const char *provider)
        return NULL;
 }
 
+static
+int check_provider_version(struct lttng_probe_desc *desc)
+{
+       /*
+        * Check tracepoint provider version compatibility.
+        */
+       if (desc->major <= LTTNG_UST_PROVIDER_MAJOR) {
+               DBG("Provider \"%s\" accepted, version %u.%u is compatible "
+                       "with LTTng UST provider version %u.%u.",
+                       desc->provider, desc->major, desc->minor,
+                       LTTNG_UST_PROVIDER_MAJOR,
+                       LTTNG_UST_PROVIDER_MINOR);
+               if (desc->major < LTTNG_UST_PROVIDER_MAJOR) {
+                       DBG("However, some LTTng UST features might not be "
+                               "available for this provider unless it is "
+                               "recompiled against a more recent LTTng UST.");
+               }
+               return 1;               /* accept */
+       } else {
+               ERR("Provider \"%s\" rejected, version %u.%u is incompatible "
+                       "with LTTng UST provider version %u.%u. Please upgrade "
+                       "LTTng UST.",
+                       desc->provider, desc->major, desc->minor,
+                       LTTNG_UST_PROVIDER_MAJOR,
+                       LTTNG_UST_PROVIDER_MINOR);
+               return 0;               /* reject */
+       }
+}
+
+
 int lttng_probe_register(struct lttng_probe_desc *desc)
 {
        int ret = 0;
 
+       /*
+        * If version mismatch, don't register, but don't trigger assert
+        * on caller. The version check just prints an error.
+        */
+       if (!check_provider_version(desc))
+               return 0;
+
        ust_lock();
 
        /*
@@ -197,6 +234,9 @@ int ltt_probe_register(struct lttng_probe_desc *desc)
 
 void lttng_probe_unregister(struct lttng_probe_desc *desc)
 {
+       if (!check_provider_version(desc))
+               return;
+
        ust_lock();
        if (!desc->lazy)
                cds_list_del(&desc->head);