Re: [PATCH 02/16] perf pmu: Let pmu's with no events show up on perf list

[Adrian Hunter]

On 24/10/2014 5:36 p.m., Adrian Hunter wrote:
> On 24/10/2014 4:21 p.m., Arnaldo Carvalho de Melo wrote:
> > Em Fri, Oct 24, 2014 at 10:03:20AM -0300, Arnaldo Carvalho de Melo escreveu:
> > > Em Fri, Oct 24, 2014 at 09:57:02AM -0300, Arnaldo Carvalho de Melo escreveu:
> > > > Em Fri, Oct 24, 2014 at 02:15:52PM +0900, Namhyung Kim escreveu:
> > > > > On Thu, 23 Oct 2014 13:45:10 +0300, Adrian Hunter wrote:
> > > > > > +        if (pmu->selectable) {
> > > > > > +            scnprintf(buf, sizeof(buf), "%s//", pmu->name);
> > > > > > +            aliases[j] = strdup(buf);
> > > > >
> > > > > You need to check the return value here (and above too).
> > > >
> > > > Well spotted, fixing this up.
> > >
> > > Oh well, this print_pmu_events() function needs some care, it starts by
> > > trying to alloc the array, if it fails, it silently returns, does that
> > > mean that there are no pmu events? Or that memory allocation failed?
> > >
> > > Ok, will do the fixes in a separate patch...
> > >
> > > - Arnaldo
> >
> > The patch below should check everything and warn the user, even
> > maintaining that void return...
> >
> > Acked-by tags welcome as always :-)
> >
> > - Arnaldo
> >
> >
> > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> > index 91dca60..881b754 100644
> > --- a/tools/perf/util/pmu.c
> > +++ b/tools/perf/util/pmu.c
> > @@ -753,9 +753,9 @@ void print_pmu_events(const char *event_glob, bool name_only)
> >           if (pmu->selectable)
> >               len++;
> >       }
> > -    aliases = malloc(sizeof(char *) * len);
> > +    aliases = zalloc(sizeof(char *) * len);
> >       if (!aliases)
> > -        return;
> > +        goto out_enomem;
>
> That path tries to free aliases[j] but aliases is null.  You could set len to 0 in that case.

Than again, no it doesn't sorry for the noise.

> >       pmu = NULL;
> >       j = 0;
> >       while ((pmu = perf_pmu__scan(pmu)) != NULL) {
> > @@ -768,16 +768,20 @@ void print_pmu_events(const char *event_glob, bool name_only)
> >                     (!is_cpu && strglobmatch(alias->name,
> >                                  event_glob))))
> >                   continue;
> > -            aliases[j] = name;
> > +
> >               if (is_cpu && !name_only)
> > -                aliases[j] = format_alias_or(buf, sizeof(buf),
> > -                                  pmu, alias);
> > -            aliases[j] = strdup(aliases[j]);
> > +                name = format_alias_or(buf, sizeof(buf), pmu, alias);
> > +
> > +            aliases[j] = strdup(name);
> > +            if (aliases[j] == NULL)
> > +                goto out_enomem;
> >               j++;
> >           }
> >           if (pmu->selectable) {
> > -            scnprintf(buf, sizeof(buf), "%s//", pmu->name);
> > -            aliases[j] = strdup(buf);
> > +            char *s;
> > +            if (asprintf(&s, "%s//", pmu->name) < 0)
> > +                goto out_enomem;
> > +            aliases[j] = s;
> >               j++;
> >           }
> >       }
> > @@ -789,12 +793,20 @@ void print_pmu_events(const char *event_glob, bool name_only)
> >               continue;
> >           }
> >           printf("  %-50s [Kernel PMU event]\n", aliases[j]);
> > -        zfree(&aliases[j]);
> >           printed++;
> >       }
> >       if (printed)
> >           printf("\n");
> > -    free(aliases);
> > +out_free:
> > +    for (j = 0; j < len; j++)
> > +        zfree(&aliases[j]);
> > +    zfree(&aliases);
> > +    return;
> > +
> > +out_enomem:
> > +    printf("FATAL: not enough memory to print PMU events\n");
> > +    if (aliases)
> > +        goto out_free;
> >   }
> >
> >   bool pmu_have_event(const char *pname, const char *name)
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