Messages in this thread Patch in this message | | | Subject | Re: [PATCH 0/7] tracing: instance_rmdir() leaks ftrace_event_file->filter | From | Namhyung Kim <> | Date | Mon, 14 Jul 2014 22:54:56 +0900 |
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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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