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>
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 @@
*/
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 @@
* 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);
};
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index b5ef0c4..bd6122c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1299,14 +1299,13 @@
FILE_RELEASE_AGENT,
};
-static ssize_t cgroup_write_u64(struct cgroup *cgrp, struct cftype *cft,
+static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft,
struct file *file,
const char __user *userbuf,
size_t nbytes, loff_t *unused_ppos)
{
char buffer[64];
int retval = 0;
- u64 val;
char *end;
if (!nbytes)
@@ -1318,12 +1317,17 @@
buffer[nbytes] = 0; /* nul-terminate */
strstrip(buffer);
- val = simple_strtoull(buffer, &end, 0);
- if (*end)
- return -EINVAL;
-
- /* Pass to subsystem */
- retval = cft->write_u64(cgrp, cft, val);
+ if (cft->write_u64) {
+ u64 val = simple_strtoull(buffer, &end, 0);
+ if (*end)
+ return -EINVAL;
+ retval = cft->write_u64(cgrp, cft, val);
+ } else {
+ s64 val = simple_strtoll(buffer, &end, 0);
+ if (*end)
+ return -EINVAL;
+ retval = cft->write_s64(cgrp, cft, val);
+ }
if (!retval)
retval = nbytes;
return retval;
@@ -1404,8 +1408,8 @@
return -ENODEV;
if (cft->write)
return cft->write(cgrp, cft, file, buf, nbytes, ppos);
- if (cft->write_u64)
- return cgroup_write_u64(cgrp, cft, file, buf, nbytes, ppos);
+ if (cft->write_u64 || cft->write_s64)
+ return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos);
return -EINVAL;
}
@@ -1421,6 +1425,18 @@
return simple_read_from_buffer(buf, nbytes, ppos, tmp, len);
}
+static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft,
+ struct file *file,
+ char __user *buf, size_t nbytes,
+ loff_t *ppos)
+{
+ char tmp[64];
+ s64 val = cft->read_s64(cgrp, cft);
+ int len = sprintf(tmp, "%lld\n", (long long) val);
+
+ return simple_read_from_buffer(buf, nbytes, ppos, tmp, len);
+}
+
static ssize_t cgroup_common_file_read(struct cgroup *cgrp,
struct cftype *cft,
struct file *file,
@@ -1477,6 +1493,8 @@
return cft->read(cgrp, cft, file, buf, nbytes, ppos);
if (cft->read_u64)
return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos);
+ if (cft->read_s64)
+ return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos);
return -EINVAL;
}