From: Pavel Emelyanov Trigger callback can be used to receive a kick-up from the user space. The string written is ignored. The cftype->private is used for multiplexing events. Signed-off-by: Pavel Emelyanov Acked-by: Paul Menage Acked-by: KAMEZAWA Hiroyuki Cc: Balbir Singh Signed-off-by: Andrew Morton --- include/linux/cgroup.h | 8 ++++++++ kernel/cgroup.c | 4 ++++ 2 files changed, 12 insertions(+) diff -puN include/linux/cgroup.h~cgroups-add-the-trigger-callback-to-struct-cftype include/linux/cgroup.h --- a/include/linux/cgroup.h~cgroups-add-the-trigger-callback-to-struct-cftype +++ a/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 -puN kernel/cgroup.c~cgroups-add-the-trigger-callback-to-struct-cftype kernel/cgroup.c --- a/kernel/cgroup.c~cgroups-add-the-trigger-callback-to-struct-cftype +++ a/kernel/cgroup.c @@ -1410,6 +1410,10 @@ static ssize_t cgroup_file_write(struct 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; } _