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-rw-r--r--include/linux/cgroup.h8
-rw-r--r--kernel/cgroup.c4
2 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 785a01c..2d1d151 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -243,6 +243,14 @@ struct cftype {
*/
int (*write_s64) (struct cgroup *cgrp, struct cftype *cft, s64 val);
+ /*
+ * trigger() callback can be used to get some kick from the
+ * userspace, when the actual string written is not important
+ * at all. The private field can be used to determine the
+ * kick type for multiplexing.
+ */
+ int (*trigger)(struct cgroup *cgrp, unsigned int event);
+
int (*release) (struct inode *inode, struct file *file);
};
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 436e26f..7c8cc51 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1410,6 +1410,10 @@ static ssize_t cgroup_file_write(struct file *file, const char __user *buf,
return cft->write(cgrp, cft, file, buf, nbytes, ppos);
if (cft->write_u64 || cft->write_s64)
return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos);
+ if (cft->trigger) {
+ int ret = cft->trigger(cgrp, (unsigned int)cft->private);
+ return ret ? ret : nbytes;
+ }
return -EINVAL;
}