On Fri, 2013-09-13 at 16:01 -0400, Steven Rostedt wrote:
> On Sat, 7 Sep 2013 10:29:00 -0500
> Tom Zanussi <[email protected]> wrote:
>
>
> > --- a/kernel/trace/trace_events_trigger.c
> > +++ b/kernel/trace/trace_events_trigger.c
> > @@ -696,6 +696,74 @@ static struct event_command trigger_traceoff_cmd = {
> > .get_trigger_ops = onoff_get_trigger_ops,
> > };
> >
> > +static void
> > +snapshot_trigger(struct event_trigger_data *data)
> > +{
> > + tracing_snapshot();
> > +}
>
> If CONFIG_TRACER_SNAPSHOT is not defined, then we should not bother
> implementing the snapshot trigger. This should be encapsulated around
> ifdefs.
OK, I guess I was just trying to avoid the ifdef since
tracing_snapshot() is already ifdef'ed out (but with a WARN_ONCE()) if
CONFIG_TRACER_SNAPSHOT isn't defined.
I agree though, it would be better to just ignore all the snapshot
trigger code if that's the case. Same for the stacktrace trigger,
though as much as I hate to put big ifdefs in the main code...
>
> > +
> > +static void
> > +snapshot_count_trigger(struct event_trigger_data *data)
> > +{
> > + if (!data->count)
> > + return;
> > +
> > + if (data->count != -1)
> > + (data->count)--;
> > +
> > + snapshot_trigger(data);
> > +}
> > +
> > +static int
> > +register_snapshot_trigger(char *glob, struct event_trigger_ops *ops,
> > + struct event_trigger_data *data,
> > + struct ftrace_event_file *file)
> > +{
> > + int ret = register_trigger(glob, ops, data, file);
> > +
> > + if (ret > 0)
> > + ftrace_alloc_snapshot();
> > +
> > + return ret;
> > +}
> > +
> > +static int
> > +snapshot_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
> > + struct event_trigger_data *data)
> > +{
> > + return event_trigger_print("snapshot", m, (void *)data->count,
> > + data->filter_str);
> > +}
> > +
> > +static struct event_trigger_ops snapshot_trigger_ops = {
> > + .func = snapshot_trigger,
> > + .print = snapshot_trigger_print,
> > + .init = event_trigger_init,
> > + .free = event_trigger_free,
> > +};
> > +
> > +static struct event_trigger_ops snapshot_count_trigger_ops = {
> > + .func = snapshot_count_trigger,
> > + .print = snapshot_trigger_print,
> > + .init = event_trigger_init,
> > + .free = event_trigger_free,
> > +};
> > +
> > +static struct event_trigger_ops *
> > +snapshot_get_trigger_ops(char *cmd, char *param)
> > +{
> > + return param ? &snapshot_count_trigger_ops : &snapshot_trigger_ops;
> > +}
> > +
> > +static struct event_command trigger_snapshot_cmd = {
> > + .name = "snapshot",
> > + .trigger_type = ETT_SNAPSHOT,
> > + .func = event_trigger_callback,
> > + .reg = register_snapshot_trigger,
> > + .unreg = unregister_trigger,
> > + .get_trigger_ops = snapshot_get_trigger_ops,
> > +};
> > +
> > static __init void unregister_trigger_traceon_traceoff_cmds(void)
> > {
> > unregister_event_command(&trigger_traceon_cmd);
> > @@ -726,5 +794,11 @@ __init int register_trigger_cmds(void)
> > return ret;
> > }
> >
> > + ret = register_event_command(&trigger_snapshot_cmd);
> > + if (WARN_ON(ret < 0)) {
> > + unregister_trigger_traceon_traceoff_cmds();
>
> If the snapshot trigger fails, why remove the traceon_traceoff trigger
> if it succeeded? Is there some dependency that we should be worried
> about?
>
> Or is this just saying "if once trigger fails, they all fail!"?
>
Right, that's all its saying, there's no dependency. I guess it would
be fine to just continue with whatever triggers did/will register
successfully - the WARN_ON() will show the failure for a given trigger,
no need to disable everything.
Tom
> -- Steve
>
> > + return ret;
> > + }
> > +
> > return 0;
> > }
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
