rtla/trace: Add trace event filter helpers

Add a set of helper functions to allow rtla tools to filter events
in the trace instance.

Link: https://lkml.kernel.org/r/12623b1684684549d53b90f4bf66fae44584fd14.1646247211.git.bristot@kernel.org
Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Clark Williams <williams@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/tools/tracing/rtla/src/trace.c b/tools/tracing/rtla/src/trace.c
index 7f8661b..ef44bab 100644 (file)
--- a/tools/tracing/rtla/src/trace.c
+++ b/tools/tracing/rtla/src/trace.c
@@ -204,6 +204,8 @@ static void trace_events_free(struct trace_events *events)
 
                tevent = tevent->next;
 
+               if (free_event->filter)
+                       free(free_event->filter);
                if (free_event->trigger)
                        free(free_event->trigger);
                free(free_event->system);
@@ -238,6 +240,21 @@ struct trace_events *trace_event_alloc(const char *event_string)
 }
 
 /*
+ * trace_event_add_filter - record an event filter
+ */
+int trace_event_add_filter(struct trace_events *event, char *filter)
+{
+       if (event->filter)
+               free(event->filter);
+
+       event->filter = strdup(filter);
+       if (!event->filter)
+               return 1;
+
+       return 0;
+}
+
+/*
  * trace_event_add_trigger - record an event trigger action
  */
 int trace_event_add_trigger(struct trace_events *event, char *trigger)
@@ -253,6 +270,33 @@ int trace_event_add_trigger(struct trace_events *event, char *trigger)
 }
 
 /*
+ * trace_event_disable_filter - disable an event filter
+ */
+static void trace_event_disable_filter(struct trace_instance *instance,
+                                      struct trace_events *tevent)
+{
+       char filter[1024];
+       int retval;
+
+       if (!tevent->filter)
+               return;
+
+       if (!tevent->filter_enabled)
+               return;
+
+       debug_msg("Disabling %s:%s filter %s\n", tevent->system,
+                 tevent->event ? : "*", tevent->filter);
+
+       snprintf(filter, 1024, "!%s\n", tevent->filter);
+
+       retval = tracefs_event_file_write(instance->inst, tevent->system,
+                                         tevent->event, "filter", filter);
+       if (retval < 0)
+               err_msg("Error disabling %s:%s filter %s\n", tevent->system,
+                       tevent->event ? : "*", tevent->filter);
+}
+
+/*
  * trace_event_disable_trigger - disable an event trigger
  */
 static void trace_event_disable_trigger(struct trace_instance *instance,
@@ -293,6 +337,7 @@ void trace_events_disable(struct trace_instance *instance,
        while (tevent) {
                debug_msg("Disabling event %s:%s\n", tevent->system, tevent->event ? : "*");
                if (tevent->enabled) {
+                       trace_event_disable_filter(instance, tevent);
                        trace_event_disable_trigger(instance, tevent);
                        tracefs_event_disable(instance->inst, tevent->system, tevent->event);
                }
@@ -303,6 +348,41 @@ void trace_events_disable(struct trace_instance *instance,
 }
 
 /*
+ * trace_event_enable_filter - enable an event filter associated with an event
+ */
+static int trace_event_enable_filter(struct trace_instance *instance,
+                                    struct trace_events *tevent)
+{
+       char filter[1024];
+       int retval;
+
+       if (!tevent->filter)
+               return 0;
+
+       if (!tevent->event) {
+               err_msg("Filter %s applies only for single events, not for all %s:* events\n",
+                       tevent->filter, tevent->system);
+               return 1;
+       }
+
+       snprintf(filter, 1024, "%s\n", tevent->filter);
+
+       debug_msg("Enabling %s:%s filter %s\n", tevent->system,
+                 tevent->event ? : "*", tevent->filter);
+
+       retval = tracefs_event_file_write(instance->inst, tevent->system,
+                                         tevent->event, "filter", filter);
+       if (retval < 0) {
+               err_msg("Error enabling %s:%s filter %s\n", tevent->system,
+                       tevent->event ? : "*", tevent->filter);
+               return 1;
+       }
+
+       tevent->filter_enabled = 1;
+       return 0;
+}
+
+/*
  * trace_event_enable_trigger - enable an event trigger associated with an event
  */
 static int trace_event_enable_trigger(struct trace_instance *instance,
@@ -356,6 +436,9 @@ int trace_events_enable(struct trace_instance *instance,
                        return 1;
                }
 
+               retval = trace_event_enable_filter(instance, tevent);
+               if (retval)
+                       return 1;
 
                retval = trace_event_enable_trigger(instance, tevent);
                if (retval)

diff --git a/tools/tracing/rtla/src/trace.h b/tools/tracing/rtla/src/trace.h
index 856b26d..51ad344 100644 (file)
--- a/tools/tracing/rtla/src/trace.h
+++ b/tools/tracing/rtla/src/trace.h
@@ -6,8 +6,10 @@ struct trace_events {
        struct trace_events *next;
        char *system;
        char *event;
+       char *filter;
        char *trigger;
        char enabled;
+       char filter_enabled;
        char trigger_enabled;
 };
 
@@ -43,4 +45,5 @@ void trace_events_destroy(struct trace_instance *instance,
 int trace_events_enable(struct trace_instance *instance,
                          struct trace_events *events);
 
+int trace_event_add_filter(struct trace_events *event, char *filter);
 int trace_event_add_trigger(struct trace_events *event, char *trigger);