Re: [PATCH 1/4] perf timechart: Release event samples at the end

[Namhyung Kim]

On Fri, Jun 05, 2026 at 08:21:49PM -0300, Arnaldo Carvalho de Melo wrote:
> On Fri, Jun 05, 2026 at 04:11:52PM -0700, Namhyung Kim wrote:
> > Add timechart__release() to free all data structures added during the
> > sample processing.
> > 
> > Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
> > ---
> >  tools/perf/builtin-timechart.c | 54 ++++++++++++++++++++++++++++++++++
> >  1 file changed, 54 insertions(+)
> > 
> > diff --git a/tools/perf/builtin-timechart.c b/tools/perf/builtin-timechart.c
> > index 04dbb944a42720b4..7c4ace51302e260c 100644
> > --- a/tools/perf/builtin-timechart.c
> > +++ b/tools/perf/builtin-timechart.c
> > @@ -1548,6 +1548,59 @@ static void write_svg_file(struct timechart *tchart, const char *filename)
> >  	svg_close();
> >  }
> >  
> > +static void timechart__release(struct timechart *tchart)
> > +{
> > +	struct per_pid *p = tchart->all_data;
> > +	struct power_event *pwr = tchart->power_events;
> > +	struct wake_event *we = tchart->wake_events;
> > +
> > +	while (p) {
> > +		struct per_pid *next_pid = p->next;
> > +		struct per_pidcomm *c = p->all;
> > +
> > +		while (c) {
> > +			struct per_pidcomm *next_comm = c->next;
> > +			struct cpu_sample *cs = c->samples;
> > +			struct io_sample *ios = c->io_samples;
> > +
> > +			while (cs) {
> > +				struct cpu_sample *next = cs->next;
> > +
> > +				free((char *)cs->backtrace);
> 
> 				zfree()? This way if somebody has a
> 				pointer to cs and tries to use
> 				cs->backtrace after this free, it will
> 				segfault instead of using garbage or
> 				worse, setting some other unrelated
> 				struct to some cpu_sample field supposed
> 				value.

Ok, will do here and others below.

Thanks,
Namhyung

> 
> > +				free(cs);
> > +				cs = next;
> > +			}
> > +
> > +			while (ios) {
> > +				struct io_sample *next = ios->next;
> > +
> > +				free(ios);
> 
> 				io->next = NULL;
> 
> > +				ios = next;
> > +			}
> > +
> > +			free(c->comm);
> 
> 			zfree
> 
> > +			free(c);
> > +			c = next_comm;
> > +		}
> > +		p = next_pid;
> > +	}
> > +
> > +	while (pwr) {
> > +		struct power_event *next = pwr->next;
> > +
> > +		free(pwr);
> 		pwr->next = NULL;
> > +		pwr = next;
> > +	}
> > +
> > +	while (we) {
> > +		struct wake_event *next = we->next;
> > +
> > +		free((char *)we->backtrace);
> 		zfree
> > +		free(we);
> > +		we = next;
> > +	}
> > +}
> > +
> >  static int process_header(struct perf_file_section *section __maybe_unused,
> >  			  struct perf_header *ph,
> >  			  int feat,
> > @@ -2079,6 +2132,7 @@ int cmd_timechart(int argc, const char **argv)
> >  
> >  	ret = __cmd_timechart(&tchart, output_name);
> >  out:
> > +	timechart__release(&tchart);
> >  	zfree(&cpus_cstate_start_times);
> >  	zfree(&cpus_cstate_state);
> >  	zfree(&cpus_pstate_start_times);
> > -- 
> > 2.54.0.1032.g2f8565e1d1-goog