tools lib traceevent: Add pevent_unregister_event_handler()

When a plugin is unloaded it needs to unregister its handler from pevent.

So add an unregister function to do it.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1389839478-5887-2-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 2ce565a..d1973cb 100644 (file)
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -5560,6 +5560,29 @@ int pevent_register_print_function(struct pevent *pevent,
        return ret;
 }
 
+static struct event_format *pevent_search_event(struct pevent *pevent, int id,
+                                               const char *sys_name,
+                                               const char *event_name)
+{
+       struct event_format *event;
+
+       if (id >= 0) {
+               /* search by id */
+               event = pevent_find_event(pevent, id);
+               if (!event)
+                       return NULL;
+               if (event_name && (strcmp(event_name, event->name) != 0))
+                       return NULL;
+               if (sys_name && (strcmp(sys_name, event->system) != 0))
+                       return NULL;
+       } else {
+               event = pevent_find_event_by_name(pevent, sys_name, event_name);
+               if (!event)
+                       return NULL;
+       }
+       return event;
+}
+
 /**
  * pevent_register_event_handler - register a way to parse an event
  * @pevent: the handle to the pevent
@@ -5584,20 +5607,9 @@ int pevent_register_event_handler(struct pevent *pevent, int id,
        struct event_format *event;
        struct event_handler *handle;
 
-       if (id >= 0) {
-               /* search by id */
-               event = pevent_find_event(pevent, id);
-               if (!event)
-                       goto not_found;
-               if (event_name && (strcmp(event_name, event->name) != 0))
-                       goto not_found;
-               if (sys_name && (strcmp(sys_name, event->system) != 0))
-                       goto not_found;
-       } else {
-               event = pevent_find_event_by_name(pevent, sys_name, event_name);
-               if (!event)
-                       goto not_found;
-       }
+       event = pevent_search_event(pevent, id, sys_name, event_name);
+       if (event == NULL)
+               goto not_found;
 
        pr_stat("overriding event (%d) %s:%s with new print handler",
                event->id, event->system, event->name);
@@ -5637,6 +5649,79 @@ int pevent_register_event_handler(struct pevent *pevent, int id,
        return -1;
 }
 
+static int handle_matches(struct event_handler *handler, int id,
+                         const char *sys_name, const char *event_name,
+                         pevent_event_handler_func func, void *context)
+{
+       if (id >= 0 && id != handler->id)
+               return 0;
+
+       if (event_name && (strcmp(event_name, handler->event_name) != 0))
+               return 0;
+
+       if (sys_name && (strcmp(sys_name, handler->sys_name) != 0))
+               return 0;
+
+       if (func != handler->func || context != handler->context)
+               return 0;
+
+       return 1;
+}
+
+/**
+ * pevent_unregister_event_handler - unregister an existing event handler
+ * @pevent: the handle to the pevent
+ * @id: the id of the event to unregister
+ * @sys_name: the system name the handler belongs to
+ * @event_name: the name of the event handler
+ * @func: the function to call to parse the event information
+ * @context: the data to be passed to @func
+ *
+ * This function removes existing event handler (parser).
+ *
+ * If @id is >= 0, then it is used to find the event.
+ * else @sys_name and @event_name are used.
+ *
+ * Returns 0 if handler was removed successfully, -1 if event was not found.
+ */
+int pevent_unregister_event_handler(struct pevent *pevent, int id,
+                                   const char *sys_name, const char *event_name,
+                                   pevent_event_handler_func func, void *context)
+{
+       struct event_format *event;
+       struct event_handler *handle;
+       struct event_handler **next;
+
+       event = pevent_search_event(pevent, id, sys_name, event_name);
+       if (event == NULL)
+               goto not_found;
+
+       if (event->handler == func && event->context == context) {
+               pr_stat("removing override handler for event (%d) %s:%s. Going back to default handler.",
+                       event->id, event->system, event->name);
+
+               event->handler = NULL;
+               event->context = NULL;
+               return 0;
+       }
+
+not_found:
+       for (next = &pevent->handlers; *next; next = &(*next)->next) {
+               handle = *next;
+               if (handle_matches(handle, id, sys_name, event_name,
+                                  func, context))
+                       break;
+       }
+
+       if (!(*next))
+               return -1;
+
+       *next = handle->next;
+       free_handler(handle);
+
+       return 0;
+}
+
 /**
  * pevent_alloc - create a pevent handle
  */

diff --git a/tools/lib/traceevent/event-parse.h b/tools/lib/traceevent/event-parse.h
index a3beca5..c48acfb 100644 (file)
--- a/tools/lib/traceevent/event-parse.h
+++ b/tools/lib/traceevent/event-parse.h
@@ -624,6 +624,9 @@ int pevent_print_func_field(struct trace_seq *s, const char *fmt,
 int pevent_register_event_handler(struct pevent *pevent, int id,
                                  const char *sys_name, const char *event_name,
                                  pevent_event_handler_func func, void *context);
+int pevent_unregister_event_handler(struct pevent *pevent, int id,
+                                   const char *sys_name, const char *event_name,
+                                   pevent_event_handler_func func, void *context);
 int pevent_register_print_function(struct pevent *pevent,
                                   pevent_func_handler func,
                                   enum pevent_func_arg_type ret_type,