2 files changed, 36 insertions, 10 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index b40fd5ee9a76..785a01cfb49d 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);
 };
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index b5ef0c4772f7..bd6122ccc0ba 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1299,14 +1299,13 @@ enum cgroup_filetype {
         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 @@ static ssize_t cgroup_write_u64(struct cgroup *cgrp, struct cftype *cft,
 
         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 @@ static ssize_t cgroup_file_write(struct file *file, const char __user *buf,
                 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 @@ static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft,
         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 @@ static ssize_t cgroup_file_read(struct file *file, char __user *buf,
                 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;
 }