Re: [PATCH v2 2/2] trace-cmd: Reset CPU mask to its default value with "trace-cmd reset".

[Steven Rostedt <rostedt@goodmis.org>]

On Tue,  1 Oct 2019 17:57:40 +0300
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> "trace-cmd reset" command should put all ftrace config to its default
> state, but trace cpumask was not reseted. The patch sets cpumask to
> its default value - all CPUs are enabled for tracing.
> 
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> ---
>  tracecmd/trace-record.c | 35 +++++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
> 
> diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
> index 69de82a..6f3520c 100644
> --- a/tracecmd/trace-record.c
> +++ b/tracecmd/trace-record.c
> @@ -4096,6 +4096,40 @@ static void reset_clock(void)
>  		write_instance_file(instance, "trace_clock", "local", "clock");
>  }
>  
> +static void reset_cpu_mask(void)
> +{
> +	struct buffer_instance *instance;
> +	int cpus = count_cpus();
> +	int fullwords;
> +	char *buf;
> +	int bits;
> +	int len;
> +
> +	fullwords = cpus / 32;
> +	bits = cpus % 32;
> +	len = (fullwords + 1) * 9;
> +
> +	buf = malloc(len + 1);
> +	if (!buf) {
> +		warning("Unable to allocate %d bytes for cpu mask", len + 1);
> +		return;
> +	}
> +	buf[0] = '\0';
> +	if (bits) {
> +		sprintf(buf, "%x", (1 << bits) - 1);
> +	} else if (fullwords) {
> +		strcat(buf, "ffffffff");
> +		fullwords--;
> +	}
> +	while (fullwords-- > 0)
> +		strcat(buf, ",ffffffff");

I like my way because it's a little more condensed ;-)

But this works too and it's far from a fast path. As it's probably
more readable, I'll all this one.

-- Steve


> +
> +	for_all_instances(instance)
> +		write_instance_file(instance, "tracing_cpumask", buf, "cpumask");
> +
> +	free(buf);
> +}
> +
>  static void reset_event_pid(void)
>  {
>  	add_event_pid("");
> @@ -4808,6 +4842,7 @@ void trace_reset(int argc, char **argv)
>  	reset_clock();
>  	reset_event_pid();
>  	reset_max_latency_instance();
> +	reset_cpu_mask();
>  	tracecmd_remove_instances();
>  	clear_func_filters();
>  	/* restore tracing_on to 1 */