Add 'stacktrace' event_command. stacktrace event triggers are added
by the user via this command in a similar way and using practically
the same syntax as the analogous 'stacktrace' ftrace function command,
but instead of writing to the set_ftrace_filter file, the stacktrace
event trigger is written to the per-event 'trigger' files:
echo 'stacktrace' > .../tracing/events/somesys/someevent/trigger
The above command will turn on stacktraces for someevent i.e. whenever
someevent is hit, a stacktrace will be logged.
This also adds a 'count' version that limits the number of times the
command will be invoked:
echo 'stacktrace:N' > .../tracing/events/somesys/someevent/trigger
Where N is the number of times the command will be invoked.
The above command will log N stacktraces for someevent i.e. whenever
someevent is hit N times, a stacktrace will be logged.
Signed-off-by: Tom Zanussi <tom.zanu...@linux.intel.com>
---
include/linux/ftrace_event.h | 1 +
kernel/trace/trace_events_trigger.c | 72 +++++++++++++++++++++++++++++++++++++
2 files changed, 73 insertions(+)
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index bfd81f3..7b44c9e 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -320,6 +320,7 @@ enum event_trigger_type {
ETT_NONE = (0),
ETT_TRACE_ONOFF = (1 << 0),
ETT_SNAPSHOT = (1 << 1),
+ ETT_STACKTRACE = (1 << 2),
};
extern void destroy_preds(struct ftrace_event_call *call);
diff --git a/kernel/trace/trace_events_trigger.c
b/kernel/trace/trace_events_trigger.c
index f32fa31..e44fbc5 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -764,6 +764,71 @@ static struct event_command trigger_snapshot_cmd = {
.get_trigger_ops = snapshot_get_trigger_ops,
};
+/*
+ * Skip 4:
+ * ftrace_stacktrace()
+ * function_trace_probe_call()
+ * ftrace_ops_list_func()
+ * ftrace_call()
+ */
+#define STACK_SKIP 4
+
+static void
+stacktrace_trigger(struct event_trigger_data *data)
+{
+ trace_dump_stack(STACK_SKIP);
+}
+
+static void
+stacktrace_count_trigger(struct event_trigger_data *data)
+{
+ if (!data->count)
+ return;
+
+ if (data->count != -1)
+ (data->count)--;
+
+ stacktrace_trigger(data);
+}
+
+static int
+stacktrace_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
+ struct event_trigger_data *data)
+{
+ return event_trigger_print("stacktrace", m, (void *)data->count,
+ data->filter_str);
+}
+
+static struct event_trigger_ops stacktrace_trigger_ops = {
+ .func = stacktrace_trigger,
+ .print = stacktrace_trigger_print,
+ .init = event_trigger_init,
+ .free = event_trigger_free,
+};
+
+static struct event_trigger_ops stacktrace_count_trigger_ops = {
+ .func = stacktrace_count_trigger,
+ .print = stacktrace_trigger_print,
+ .init = event_trigger_init,
+ .free = event_trigger_free,
+};
+
+static struct event_trigger_ops *
+stacktrace_get_trigger_ops(char *cmd, char *param)
+{
+ return param ? &stacktrace_count_trigger_ops : &stacktrace_trigger_ops;
+}
+
+static struct event_command trigger_stacktrace_cmd = {
+ .name = "stacktrace",
+ .trigger_type = ETT_STACKTRACE,
+ .post_trigger = true,
+ .func = event_trigger_callback,
+ .reg = register_trigger,
+ .unreg = unregister_trigger,
+ .get_trigger_ops = stacktrace_get_trigger_ops,
+};
+
static __init void unregister_trigger_traceon_traceoff_cmds(void)
{
unregister_event_command(&trigger_traceon_cmd);
@@ -800,5 +865,12 @@ __init int register_trigger_cmds(void)
return ret;
}
+ ret = register_event_command(&trigger_stacktrace_cmd);
+ if (WARN_ON(ret < 0)) {
+ unregister_trigger_traceon_traceoff_cmds();
+ unregister_event_command(&trigger_snapshot_cmd);
+ return ret;
+ }
+
return 0;
}
--
1.7.11.4
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