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

> 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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