Hi Oleg,
2014-07-11 (금), 21:06 +0200, Oleg Nesterov:
> Hello,
>
> Sorry for delay, I was distracted by other problems.
>
> To remind, we discussed the potential uprobes "mix perf/ftrace" changes and
> found some off-topic problems. Lets start with ->filter fixes/cleanups.
>
> So far I didn't even try to test this series, although it looks simple except
> perhaps the last patch. I'll try to somehow test this tomorrow, but I do not
> really now how.
>
> So please review, these patches need acks anyway.
>
> As for 1/7, I added BUG_ON(file->filter) into remove_event_file_dir() before
> kmem_cache_free() to verify that yes, the leak does exist. Perhaps this patch
> should go to stable, or at least to v3.16.
>
> --------------------------------------------------------------------------------
> And could someone explain me why apply_subsystem_event_filter("0") clears
> ->filter_string first, then the whole ->filter? It seems that the only
> thing filter_free_subsystem_preds() should do is filter_disable(), no?
> IOW, why the patch below (on top of this series) is wrong?
I also think that the original code is bit strange. I agree with your
change and name of the function should be changed to something like
'filter_disable_subsystem_filters' IMHO (it does nothing with preds).
With this change, the apply_subsystem_event_filter can simply do below:
if (!strcmp(strstrip(filter_string), "0")) {
filter_disable_subsystem_filters(system, tr);
/* Ensure all filters are no longer used */
synchronize_sched();
filter_free_subsystem_filters(system, tr);
__free_filter(system->filter);
system->filter = NULL;
goto out_unlock;
}
Thanks,
Namhyung
>
> Oleg.
>
> --- x/kernel/trace/trace_events_filter.c
> +++ x/kernel/trace/trace_events_filter.c
> @@ -831,17 +831,6 @@ static int __alloc_preds(struct event_filter *filter,
> int n_preds)
> return 0;
> }
>
> -static inline void __remove_filter(struct ftrace_event_file *file)
> -{
> - struct ftrace_event_call *call = file->event_call;
> -
> - filter_disable(file);
> - if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
> - remove_filter_string(call->filter);
> - else
> - remove_filter_string(file->filter);
> -}
> -
> static void filter_free_subsystem_preds(struct event_subsystem *system,
> struct trace_array *tr)
> {
> @@ -850,7 +839,7 @@ static void filter_free_subsystem_preds(struct
> event_subsystem *system,
> list_for_each_entry(file, &tr->events, list) {
> if (file->system->subsystem != system)
> continue;
> - __remove_filter(file);
> + filter_disable(file);
> }
> }
>
>
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