On Sat, 18 Apr 2020 11:36:05 -0500
Bijan Tabatabai <bijan311@xxxxxxxxx> wrote:
> When the -F flag is used in trace-cmd record, trace-cmd stops recording
> when the executable it is tracing terminates.
> This patch makes the -P flag act similarly.
I don't mind the idea, but I'm worried about this approach.
>
> Signed-off-by: Bijan Tabatabai <bijan311@xxxxxxxxx>
> ---
> tracecmd/trace-record.c | 21 +++++++++++++++++----
> 1 file changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
> index d89b32d..b5cd4c4 100644
> --- a/tracecmd/trace-record.c
> +++ b/tracecmd/trace-record.c
> @@ -121,8 +121,10 @@ struct filter_pids {
> };
>
> static struct filter_pids *filter_pids;
> +static struct filter_pids *process_pids;
> static int nr_filter_pids;
> static int len_filter_pids;
> +static int nr_process_pids = 0;
>
> static int have_set_event_pid;
> static int have_event_fork;
> @@ -5799,7 +5801,9 @@ static void parse_record_options(int argc,
> while (pid) {
> add_filter_pid(atoi(pid), 0);
> pid = strtok_r(NULL, ",", &sav);
> + nr_process_pids++;
> }
> + process_pids = filter_pids;
> free(pids);
> break;
> case 'c':
> @@ -6273,10 +6277,19 @@ static void record_trace(int argc, char **argv,
> ptrace_attach(pid->pid);
> }
> }
> - /* sleep till we are woken with Ctrl^C */
> - printf("Hit Ctrl^C to stop recording\n");
> - while (!finished)
> - trace_or_sleep(type);
> + if (nr_process_pids) {
> + for (pid = process_pids; pid && nr_process_pids; pid = pid->next) {
> + if (!pid->exclude)
> + /* Wait for the process to end */
> + while(!kill(pid->pid, 0));
Won't that while loop just go into a spin?
What about something like a fsnotify on a /proc/<pid>/ file?
I rather have trace-cmd sleep and wake up when a task exits, than to do a
spin. Like it does for the -F option.
Thanks!
-- Steve
> + nr_process_pids--;
> + }
> + } else {
> + /* sleep till we are woken with Ctrl^C */
> + printf("Hit Ctrl^C to stop recording\n");
> + while (!finished)
> + trace_or_sleep(type);
> + }
> }
>
> tell_guests_to_stop();
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