Re: [PATCH v13 5/8] perf record: Read from overwritable ring buffer
From: Jiri Olsa
Date: Wed Jul 06 2016 - 07:39:08 EST
On Mon, Jul 04, 2016 at 06:20:06AM +0000, Wang Nan wrote:
SNIP
> +static void
> +record__toggle_overwrite_evsels(struct record *rec,
> + enum overwrite_evt_state state)
> +{
> + struct perf_evlist *evlist = rec->overwrite_evlist;
> + enum overwrite_evt_state old_state = rec->overwrite_evt_state;
> + enum action {
> + NONE,
> + PAUSE,
> + RESUME,
> + } action = NONE;
> +
> + switch (old_state) {
> + case OVERWRITE_EVT_RUNNING: {
> + switch (state) {
> + case OVERWRITE_EVT_DATA_PENDING:
> + action = PAUSE;
> + break;
> + case OVERWRITE_EVT_RUNNING:
> + case OVERWRITE_EVT_EMPTY:
> + default:
> + goto state_err;
> + }
> + break;
> + }
> + case OVERWRITE_EVT_DATA_PENDING: {
> + switch (state) {
> + case OVERWRITE_EVT_EMPTY:
> + break;
> + case OVERWRITE_EVT_RUNNING:
> + case OVERWRITE_EVT_DATA_PENDING:
> + default:
> + goto state_err;
> + }
> + break;
> + }
> + case OVERWRITE_EVT_EMPTY: {
> + switch (state) {
> + case OVERWRITE_EVT_RUNNING:
> + action = RESUME;
> + break;
> + case OVERWRITE_EVT_EMPTY:
> + case OVERWRITE_EVT_DATA_PENDING:
> + default:
> + goto state_err;
> + }
> + break;
> + }
> + default:
> + WARN_ONCE(1, "Shouldn't get there\n");
> + }
> +
> + rec->overwrite_evt_state = state;
> +
> + if (!evlist)
> + return;
I'd expect this check at the begining
jirka