perf/core: Add attr_groups_update into struct pmu

Adding attr_update attribute group into pmu, to allow
having multiple attribute groups for same group name.

This will allow us to update "events" or "format"
directories with attributes that depend on various
HW conditions.

For example having group_format_extra group that updates
"format" directory only if pmu version is 2 and higher:

  static umode_t
  exra_is_visible(struct kobject *kobj, struct attribute *attr, int i)
  {
         return x86_pmu.version >= 2 ? attr->mode : 0;
  }

  static struct attribute_group group_format_extra = {
         .name       = "format",
         .is_visible = exra_is_visible,
  };

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190512155518.21468-3-jolsa@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 0ab99c7..3dc01cf 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -255,6 +255,7 @@ struct pmu {
        struct module                   *module;
        struct device                   *dev;
        const struct attribute_group    **attr_groups;
+       const struct attribute_group    **attr_update;
        const char                      *name;
        int                             type;
 

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 3005c80..118ad1a 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9874,6 +9874,12 @@ static int pmu_dev_alloc(struct pmu *pmu)
        if (ret)
                goto del_dev;
 
+       if (pmu->attr_update)
+               ret = sysfs_update_groups(&pmu->dev->kobj, pmu->attr_update);
+
+       if (ret)
+               goto del_dev;
+
 out:
        return ret;