Re: [PATCH] perf test: Test libpfm4 support (63) reports error

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, May 18, 2021 at 04:30:35PM -0700, Ian Rogers escreveu:
> On Mon, May 17, 2021 at 7:12 AM Thomas Richter <tmricht@linux.ibm.com> wrote:
> >
> > Compiling perf with make LIBPFM4=1 includes libpfm support and
> > enables test case 63 'Test libpfm4 support'. This test reports an error
> > on all platforms for subtest 63.2 'test groups of --pfm-events'.
> > The reported error message is 'nested event groups not supported'
> 
> The parsing test checks broken and working strings and so errors are
> always going to be reported, but agreed this error is wrong.
> 
> >  # ./perf test -F 63
> >  63: Test libpfm4 support                                            :
> >  63.1: test of individual --pfm-events                               :
> >  Error:
> >  failed to parse event stereolab : event not found
> >  Error:
> >  failed to parse event stereolab,instructions : event not found
> >  Error:
> >  failed to parse event instructions,stereolab : event not found
> >   Ok
> >  63.2: test groups of --pfm-events                                   :
> >  Error:
> >  nested event groups not supported    <------ Error message here
> >  Error:
> >  failed to parse event {stereolab} : event not found
> >  Error:
> >  failed to parse event {instructions,cycles},{instructions,stereolab} :\
> >          event not found
> >  Ok
> >  #
> >
> > This patch addresses the error message 'nested event groups not supported'.
> > The root cause is function parse_libpfm_events_option() which parses the
> > event string '{},{instructions}' and can not handle a leading empty
> > group notation '{},...'.
> >
> > The code detects the first (empty) group indicator '{' but does not
> > terminate group processing on the following group closing character '}'.
> > So when the second group indicator '{' is detected, the code assumes
> > a nested group and returns an error.
> >
> > With the error message fixed, also change the expected event number to
> > one for the test case to succeed.
> >
> > While at it also fix a memory leak. In good case the function does not
> > free the duplicated string given as first parameter.
> >
> > Output after:
> >  # ./perf test -F 63
> >  63: Test libpfm4 support                                            :
> >  63.1: test of individual --pfm-events                               :
> >  Error:
> >  failed to parse event stereolab : event not found
> >  Error:
> >  failed to parse event stereolab,instructions : event not found
> >  Error:
> >  failed to parse event instructions,stereolab : event not found
> >   Ok
> >  63.2: test groups of --pfm-events                                   :
> >  Error:
> >  failed to parse event {stereolab} : event not found
> >  Error:
> >  failed to parse event {instructions,cycles},{instructions,stereolab} : \
> >          event not found
> >   Ok
> >  #
> > Error message 'nested event groups not supported' is gone.
> 
> Acked-By: Ian Rogers <irogers@google.com>
> 
> I wonder if we should add some coverage for the error cases to the pfm
> test with something like the following.

Yeah, agreed, please consider sending a patch for that.

Thanks, applied.

- Arnaldo
 
> Thanks,
> Ian
> 
> --- a/tools/perf/tests/pfm.c
> +++ b/tools/perf/tests/pfm.c
> @@ -155,6 +155,16 @@ static int test__pfm_group(void)
>                         .nr_events = 3,
>                         .nr_groups = 1,
>                 },
> +               {
> +                       .events = "instructions}",
> +                       .nr_events = 1,
> +                       .nr_groups = 0,
> +               },
> +               {
> +                       .events = "{{instructions}}",
> +                       .nr_events = 0,
> +                       .nr_groups = 0,
> +               },
>         };
> 
>         for (i = 0; i < ARRAY_SIZE(table); i++) {
> 
> > Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
> > Acked-By: Sumanth Korikkar <sumanthk@linux.ibm.com>
> > ---
> >  tools/perf/tests/pfm.c |  4 ++--
> >  tools/perf/util/pfm.c  | 11 ++++++++++-
> >  2 files changed, 12 insertions(+), 3 deletions(-)
> >
> > diff --git a/tools/perf/tests/pfm.c b/tools/perf/tests/pfm.c
> > index 76a53126efdf..d4b0ef74defc 100644
> > --- a/tools/perf/tests/pfm.c
> > +++ b/tools/perf/tests/pfm.c
> > @@ -131,8 +131,8 @@ static int test__pfm_group(void)
> >                 },
> >                 {
> >                         .events = "{},{instructions}",
> > -                       .nr_events = 0,
> > -                       .nr_groups = 0,
> > +                       .nr_events = 1,
> > +                       .nr_groups = 1,
> >                 },
> >                 {
> >                         .events = "{instructions},{instructions}",
> > diff --git a/tools/perf/util/pfm.c b/tools/perf/util/pfm.c
> > index d735acb6c29c..6eef6dfeaa57 100644
> > --- a/tools/perf/util/pfm.c
> > +++ b/tools/perf/util/pfm.c
> > @@ -62,8 +62,16 @@ int parse_libpfm_events_option(const struct option *opt, const char *str,
> >                 }
> >
> >                 /* no event */
> > -               if (*q == '\0')
> > +               if (*q == '\0') {
> > +                       if (*sep == '}') {
> > +                               if (grp_evt < 0) {
> > +                                       ui__error("cannot close a non-existing event group\n");
> > +                                       goto error;
> > +                               }
> > +                               grp_evt--;
> > +                       }
> >                         continue;
> > +               }
> >
> >                 memset(&attr, 0, sizeof(attr));
> >                 event_attr_init(&attr);
> > @@ -107,6 +115,7 @@ int parse_libpfm_events_option(const struct option *opt, const char *str,
> >                         grp_evt = -1;
> >                 }
> >         }
> > +       free(p_orig);
> >         return 0;
> >  error:
> >         free(p_orig);
> > --
> > 2.31.1
> >

-- 

- Arnaldo