linux-kernel - Re: [PATCH v10 07/10] perf record: Read from overwritable ring buffer

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Message-ID: <CACbG30-YC1AN43mtkZbuyAq0YiE9YBknbhXRrYO7TYn3SoQFPw@mail.gmail.com>
Date:	Thu, 23 Jun 2016 09:27:32 -0500
From:	Nilay Vaish <nilayvaish@...il.com>
To:	Wang Nan <wangnan0@...wei.com>
Cc:	acme@...nel.org, Linux Kernel list <linux-kernel@...r.kernel.org>,
	pi3orama@....com, He Kuang <hekuang@...wei.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Zefan Li <lizefan@...wei.com>
Subject: Re: [PATCH v10 07/10] perf record: Read from overwritable ring buffer

On 23 June 2016 at 00:27, Wang Nan <wangnan0@...wei.com> wrote:
> @@ -542,6 +568,79 @@ static struct perf_event_header finished_round_event = {
>         .type = PERF_RECORD_FINISHED_ROUND,
>  };
>
> +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;


Wang, thanks for making the changes I suggested.
The patch overall looks fine to me.  Just as a matter
of style, I probably would not write case labels that
do not have any statements associated with them.
I'll let default take care of those labels.

--
Nilay