Add cgroup write_uint() helper method

Add write_uint() helper method for cgroup subsystems

This helper is analagous to the read_uint() helper method for
reporting u64 values to userspace. It's designed to reduce the amount
of boilerplate requierd for creating new cgroup subsystems.

Signed-off-by: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index e2dd44f68f97..e95143c884b2 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -125,6 +125,14 @@ struct cftype {
 	ssize_t (*write) (struct cgroup *cont, struct cftype *cft,
 			  struct file *file,
 			  const char __user *buf, size_t nbytes, loff_t *ppos);
+
+	/*
+	 * write_uint() is a shortcut for the common case of accepting
+	 * a single integer (as parsed by simple_strtoull) from
+	 * userspace. Use in place of write(); return 0 or error.
+	 */
+	int (*write_uint) (struct cgroup *cont, struct cftype *cft, u64 val);
+
 	int (*release) (struct inode *inode, struct file *file);
 };