Support unloading of probe providers

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

diff --git a/liblttng-ust/lttng-probes.c b/liblttng-ust/lttng-probes.c
index f028ccab8cadd967971cb3f673b883f622b03f7e..862b19e7c47e3c7c5b5e262e5b1bc02edf3c090f 100644 (file)
--- a/liblttng-ust/lttng-probes.c
+++ b/liblttng-ust/lttng-probes.c
@@ -20,6 +20,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#define _LGPL_SOURCE
 #include <string.h>
 #include <errno.h>
 #include <urcu/list.h>
@@ -147,32 +148,50 @@ struct cds_list_head *lttng_get_probe_list_head(void)
 }
 
 static
-const struct lttng_probe_desc *find_provider(const char *provider)
+int check_provider_version(struct lttng_probe_desc *desc)
 {
-       struct lttng_probe_desc *iter;
-       struct cds_list_head *probe_list;
-
-       probe_list = lttng_get_probe_list_head();
-       cds_list_for_each_entry(iter, probe_list, head) {
-               if (!strcmp(iter->provider, provider))
-                       return iter;
+       /*
+        * 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 */
        }
-       return NULL;
 }
 
+
 int lttng_probe_register(struct lttng_probe_desc *desc)
 {
        int ret = 0;
 
-       ust_lock();
+       lttng_ust_fixup_tls();
 
        /*
-        * Check if the provider has already been registered.
+        * If version mismatch, don't register, but don't trigger assert
+        * on caller. The version check just prints an error.
         */
-       if (find_provider(desc->provider)) {
-               ret = -EEXIST;
-               goto end;
-       }
+       if (!check_provider_version(desc))
+               return 0;
+
+       ust_lock_nocheck();
+
        cds_list_add(&desc->lazy_init_head, &lazy_probe_init);
        desc->lazy = 1;
        DBG("adding probe %s containing %u events to lazy registration list",
@@ -184,7 +203,7 @@ int lttng_probe_register(struct lttng_probe_desc *desc)
         */
        if (lttng_session_active())
                fixup_lazy_probes();
-end:
+
        ust_unlock();
        return ret;
 }
@@ -197,12 +216,20 @@ int ltt_probe_register(struct lttng_probe_desc *desc)
 
 void lttng_probe_unregister(struct lttng_probe_desc *desc)
 {
-       ust_lock();
+       lttng_ust_fixup_tls();
+
+       if (!check_provider_version(desc))
+               return;
+
+       ust_lock_nocheck();
        if (!desc->lazy)
                cds_list_del(&desc->head);
        else
                cds_list_del(&desc->lazy_init_head);
-       DBG("just unregistered probe %s", desc->provider);
+
+       lttng_probe_provider_unregister_events(desc);
+       DBG("just unregistered probes of provider %s", desc->provider);
+
        ust_unlock();
 }