Re: [PATCH v6 04/10] libperf: Add evsel mmap support

Rob Herring
2021-03-12T14:36:23Z

On Fri, Mar 12, 2021 at 6:59 AM Jiri Olsa <jolsa@redhat.com> wrote:
>
> On Wed, Mar 10, 2021 at 05:08:31PM -0700, Rob Herring wrote:
>
> SNIP
>
> > +
> > static int
> > sys_perf_event_open(struct perf_event_attr *attr,
> > pid_t pid, int cpu, int group_fd,
> > @@ -137,6 +147,8 @@ void perf_evsel__free_fd(struct perf_evsel *evsel)
> > {
> > xyarray__delete(evsel->fd);
> > evsel->fd = NULL;
> > + xyarray__delete(evsel->mmap);
> > + evsel->mmap = NULL;
> > }
> >
> > void perf_evsel__close(struct perf_evsel *evsel)
> > @@ -156,6 +168,45 @@ void perf_evsel__close_cpu(struct perf_evsel *evsel, int cpu)
> > perf_evsel__close_fd_cpu(evsel, cpu);
> > }
> >
> > +int perf_evsel__mmap(struct perf_evsel *evsel, int pages)
> > +{
> > + int ret, cpu, thread;
> > + struct perf_mmap_param mp = {
> > + .prot = PROT_READ | PROT_WRITE,
> > + .mask = (pages * page_size) - 1,
> > + };
>
> I don't mind using evsel->fd for dimensions below,
> but we need to check in here that it's defined,
> that perf_evsel__open was called

Right, so I'll add this here:

if (evsel->fd == NULL)
return -EINVAL;

Note that struct evsel has dimensions in it, but they are only set in
the evlist code. I couldn't tell if that was by design or mistake.

BTW, I just noticed perf_evsel__open is leaking memory on most of its
error paths.

>
> jirka
>
> > +
> > + if (evsel->mmap == NULL &&
> > + perf_evsel__alloc_mmap(evsel, xyarray__max_x(evsel->fd), xyarray__max_y(evsel->fd)) < 0)
> > + return -ENOMEM;
> > +
> > + for (cpu = 0; cpu < xyarray__max_x(evsel->fd); cpu++) {
> > + for (thread = 0; thread < xyarray__max_y(evsel->fd); thread++) {
> > + int fd = FD(evsel, cpu, thread);
> > + struct perf_mmap *map = MMAP(evsel, cpu, thread);
> > +
> > + if (fd < 0)
> > + continue;
> > +
> > + perf_mmap__init(map, NULL, false, NULL);
> > +
> > + ret = perf_mmap__mmap(map, &mp, fd, cpu);
> > + if (ret)
> > + return -1;
> > + }
> > + }
> > +
> > + return 0;
> > +}
> > +
>
> SNIP