Messages in this thread | | | Date | Fri, 11 Dec 2015 17:59:04 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v0 3/5] perf: Introduce instruction trace filtering |
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On Fri, Dec 11, 2015 at 03:36:36PM +0200, Alexander Shishkin wrote: > +static int > +perf_event_set_itrace_filter(struct perf_event *event, char *filter_str) > +{ > + int ret = 0; > + > + /* > + * Since this is called in perf_ioctl() path, we're already holding > + * ctx::mutex. > + */ > + lockdep_assert_held(&event->ctx->mutex); > + > + /* > + * For now, we only support filtering in per-task events; doing so > + * for cpu-wide events requires additional context switching trickery, > + * since same object code will be mapped at different virtual > + * addresses in different processes. > + */ > + if (!event->ctx->task) > + return -EOPNOTSUPP; > + > + /* remove existing filters, if any */ > + perf_itrace_filters_clear(event); > + > + ret = perf_event_parse_itrace_filter(event, filter_str); > + if (!ret) { > + perf_itrace_filters_apply(event); > + > + ret = perf_event_itrace_filters_setup(event); > + if (ret) > + perf_itrace_filters_clear(event);
This is what I meant, if you try and set a 'wrong' filter while it already has filters set, you'll not only error out, you'll also wipe the current state.
This seems wrong.
> + } > + > + return ret; > +}
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