Re: [PATCH 01/10] perf, tools: Dont stop PMU parsing on alias parse error

Jiri Olsa
2015-12-21T16:09:03Z

On Tue, Dec 15, 2015 at 04:54:17PM -0800, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> When an error happens during alias parsing currently the complete
> parsing of all attributes of the PMU is stopped. This is breaks
> old perf on a newer kernel that may have not-yet-know
> alias attributes (such as .scale or .per-pkg).

I kind of recall seeing similar patch, but looks like
it never made it in

>
> Continue when some attribute is unparseable.
>
> This is IMHO a stable candidate and should be backported
> to older versions to avoid problems with newer kernels.
>
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
> tools/perf/util/pmu.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index e4b173d..8a520e9 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -283,13 +283,12 @@ static int pmu_aliases_parse(char *dir, struct list_head *head)
> {
> struct dirent *evt_ent;
> DIR *event_dir;
> - int ret = 0;
>
> event_dir = opendir(dir);
> if (!event_dir)
> return -EINVAL;
>
> - while (!ret && (evt_ent = readdir(event_dir))) {
> + while ((evt_ent = readdir(event_dir))) {
> char path[PATH_MAX];
> char *name = evt_ent->d_name;
> FILE *file;
> @@ -305,17 +304,16 @@ static int pmu_aliases_parse(char *dir, struct list_head *head)
>
> snprintf(path, PATH_MAX, "%s/%s", dir, name);
>
> - ret = -EINVAL;
> file = fopen(path, "r");
> if (!file)
> - break;
> + continue;

I think we should emit warning in case of failure to let user know

>
> - ret = perf_pmu__new_alias(head, dir, name, file);

same here

> + perf_pmu__new_alias(head, dir, name, file);
> fclose(file);
> }
>

thanks,
jirka