CGroups _s64 files: add cgroups read_s64/write_s64 file methods

These patches add cgroups read_s64 and write_s64 control file methods (the
signed equivalent of read_u64/write_u64) and use them to implement the
cpu.rt_runtime_us control file in the CFS cgroup subsystem.

This patch:

These are the signed equivalents of the read_u64/write_u64 methods

Signed-off-by: Paul Menage <menage@google.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
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 b40fd5e..785a01c 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -216,6 +216,10 @@ struct cftype {
 	 */
 	u64 (*read_u64) (struct cgroup *cgrp, struct cftype *cft);
 	/*
+	 * read_s64() is a signed version of read_u64()
+	 */
+	s64 (*read_s64) (struct cgroup *cgrp, struct cftype *cft);
+	/*
 	 * read_map() is used for defining a map of key/value
 	 * pairs. It should call cb->fill(cb, key, value) for each
 	 * entry. The key/value pairs (and their ordering) should not
@@ -234,6 +238,10 @@ struct cftype {
 	 * userspace. Use in place of write(); return 0 or error.
 	 */
 	int (*write_u64) (struct cgroup *cgrp, struct cftype *cft, u64 val);
+	/*
+	 * write_s64() is a signed version of write_u64()
+	 */
+	int (*write_s64) (struct cgroup *cgrp, struct cftype *cft, s64 val);
 
 	int (*release) (struct inode *inode, struct file *file);
 };