[tip:perf/core] sysfs: Add sysfs_update_groups function

[tip-bot for Jiri Olsa <tipbot@zytor.com>]

Commit-ID:  aac1f7f95f115d5a5329be05b80022e72df7d080
Gitweb:     https://git.kernel.org/tip/aac1f7f95f115d5a5329be05b80022e72df7d080
Author:     Jiri Olsa <jolsa@kernel.org>
AuthorDate: Sun, 12 May 2019 17:55:10 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 3 Jun 2019 11:58:20 +0200

sysfs: Add sysfs_update_groups function

Adding sysfs_update_groups function to update
multiple groups.

  sysfs_update_groups - given a directory kobject, create a bunch of attribute groups
  @kobj:      The kobject to update the group on
  @groups:    The attribute groups to update, NULL terminated

This function update a bunch of attribute groups.  If an error occurs when
updating a group, all previously updated groups will be removed together
with already existing (not updated) attributes.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.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/20190512155518.21468-2-jolsa@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 fs/sysfs/group.c      | 54 +++++++++++++++++++++++++++++++++++++--------------
 include/linux/sysfs.h |  8 ++++++++
 2 files changed, 47 insertions(+), 15 deletions(-)

diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index 57038604d4a8..d41c21fef138 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -175,6 +175,26 @@ int sysfs_create_group(struct kobject *kobj,
 }
 EXPORT_SYMBOL_GPL(sysfs_create_group);
 
+static int internal_create_groups(struct kobject *kobj, int update,
+				  const struct attribute_group **groups)
+{
+	int error = 0;
+	int i;
+
+	if (!groups)
+		return 0;
+
+	for (i = 0; groups[i]; i++) {
+		error = internal_create_group(kobj, update, groups[i]);
+		if (error) {
+			while (--i >= 0)
+				sysfs_remove_group(kobj, groups[i]);
+			break;
+		}
+	}
+	return error;
+}
+
 /**
  * sysfs_create_groups - given a directory kobject, create a bunch of attribute groups
  * @kobj:	The kobject to create the group on
@@ -191,24 +211,28 @@ EXPORT_SYMBOL_GPL(sysfs_create_group);
 int sysfs_create_groups(struct kobject *kobj,
 			const struct attribute_group **groups)
 {
-	int error = 0;
-	int i;
-
-	if (!groups)
-		return 0;
-
-	for (i = 0; groups[i]; i++) {
-		error = sysfs_create_group(kobj, groups[i]);
-		if (error) {
-			while (--i >= 0)
-				sysfs_remove_group(kobj, groups[i]);
-			break;
-		}
-	}
-	return error;
+	return internal_create_groups(kobj, 0, groups);
 }
 EXPORT_SYMBOL_GPL(sysfs_create_groups);
 
+/**
+ * sysfs_update_groups - given a directory kobject, create a bunch of attribute groups
+ * @kobj:	The kobject to update the group on
+ * @groups:	The attribute groups to update, NULL terminated
+ *
+ * This function update a bunch of attribute groups.  If an error occurs when
+ * updating a group, all previously updated groups will be removed together
+ * with already existing (not updated) attributes.
+ *
+ * Returns 0 on success or error code from sysfs_update_group on failure.
+ */
+int sysfs_update_groups(struct kobject *kobj,
+			const struct attribute_group **groups)
+{
+	return internal_create_groups(kobj, 1, groups);
+}
+EXPORT_SYMBOL_GPL(sysfs_update_groups);
+
 /**
  * sysfs_update_group - given a directory kobject, update an attribute group
  * @kobj:	The kobject to update the group on
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 786816cf4aa5..965236795750 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -268,6 +268,8 @@ int __must_check sysfs_create_group(struct kobject *kobj,
 				    const struct attribute_group *grp);
 int __must_check sysfs_create_groups(struct kobject *kobj,
 				     const struct attribute_group **groups);
+int __must_check sysfs_update_groups(struct kobject *kobj,
+				     const struct attribute_group **groups);
 int sysfs_update_group(struct kobject *kobj,
 		       const struct attribute_group *grp);
 void sysfs_remove_group(struct kobject *kobj,
@@ -433,6 +435,12 @@ static inline int sysfs_create_groups(struct kobject *kobj,
 	return 0;
 }
 
+static inline int sysfs_update_groups(struct kobject *kobj,
+				      const struct attribute_group **groups)
+{
+	return 0;
+}
+
 static inline int sysfs_update_group(struct kobject *kobj,
 				const struct attribute_group *grp)
 {