Re: [PATCH] trace/simple: Enable tracing on startup only if the user specifies a trace option

[Markus Armbruster]

duboisj@gmail.com writes:

> From: Josh DuBois <josh@joshdubois.com>
>
> Tracing can be enabled at the command line or via the
> monitor. Command-line trace options are recorded during
> trace_opt_parse(), but tracing is not enabled until the various
> front-ends later call trace_init_file(). If the user passes a trace
> option on the command-line, remember that and enable tracing during
> trace_init_file().  Otherwise, trace_init_file() should record the
> trace file specified by the frontend and avoid enabling traces
> until the user requests them via the monitor.
>
> This fixes 1b7157be3a8c4300fc8044d40f4b2e64a152a1b4 and also
> db25d56c014aa1a96319c663e0a60346a223b31e, by allowing the user
> to enable traces on the command line and also avoiding
> unwanted trace-<pid> files when the user has not asked for them.
>
> Fixes: 1b7157be3a8c4300fc8044d40f4b2e64a152a1b4
> Signed-off-by: Josh DuBois <josh@joshdubois.com>
> ---
>  trace/control.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/trace/control.c b/trace/control.c
> index 6558b5c906..8f94f09444 100644
> --- a/trace/control.c
> +++ b/trace/control.c
> @@ -39,6 +39,7 @@ static TraceEventGroup *event_groups;
>  static size_t nevent_groups;
>  static uint32_t next_id;
>  static uint32_t next_vcpu_id;
> +static bool init_trace_on_startup;
>  
>  QemuOptsList qemu_trace_opts = {
>      .name = "trace",
> @@ -225,7 +226,9 @@ void trace_init_file(const char *file)
>  {
>  #ifdef CONFIG_TRACE_SIMPLE
>      st_set_trace_file(file);
> -    st_set_trace_file_enabled(true);
> +    if (init_trace_on_startup) {
> +        st_set_trace_file_enabled(true);
> +    }
>  #elif defined CONFIG_TRACE_LOG
>      /*
>       * If both the simple and the log backends are enabled, "--trace file"
> @@ -299,6 +302,7 @@ char *trace_opt_parse(const char *optarg)
>      }
>      trace_init_events(qemu_opt_get(opts, "events"));
>      trace_file = g_strdup(qemu_opt_get(opts, "file"));
> +    init_trace_on_startup = true;
>      qemu_opts_del(opts);
>  
>      return trace_file;

Stops the littering for me.

Stefan, please have a closer look.