[tip:perf/core] perf/core: Add attr_groups_update into struct pmu

[tip-bot for Jiri Olsa]

Commit-ID:  f3a3a8257e5a1a5e67cbb1afdbc4c1c6a26f1b22
Gitweb:     https://git.kernel.org/tip/f3a3a8257e5a1a5e67cbb1afdbc4c1c6a26f1b22
Author:     Jiri Olsa <jolsa@xxxxxxxxxx>
AuthorDate: Sun, 12 May 2019 17:55:11 +0200
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 3 Jun 2019 11:58:21 +0200

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@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20190512155518.21468-3-jolsa@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 include/linux/perf_event.h | 1 +
 kernel/events/core.c       | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 0ab99c7b652d..3dc01cf98e16 100644
--- 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 3005c80f621d..118ad1aef6af 100644
--- 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;