Re: [PATCH v15 09/12] perf record: Read from overwritable ring buffer

Jiri Olsa
2016-07-13T14:08:18Z

On Tue, Jul 12, 2016 at 10:00:09AM +0000, Wang Nan wrote:

SBIP

> + default:
> + goto state_err;
> + }
> + break;
> + }
> + default:
> + WARN_ONCE(1, "Shouldn't get there\n");
> + }
> +
> + rec->overwrite_evt_state = state;
> +
> + switch (action) {
> + case PAUSE:
> + perf_evlist__pause(rec->evlist);
> + break;
> + case RESUME:
> + perf_evlist__resume(rec->evlist);
> + break;

so this is called on evlist with uninitialized backward_mmap,
which makes above calls fail, but luckily we dont check the
return values

I think we could set some evlist flag to know we have backward
mmaps and skip this function completely if we dont have any

thanks,
jirka