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memcg: rename cgroup_event to mem_cgroup_event

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cgroup_event is only available in memcg now.  Let's brand it that way.
While at it, add a comment encouraging deprecation of the feature and
remove the respective section from cgroup documentation.

This patch is cosmetic.

v3: Typo update as per Li Zefan.

v2: Index in cgroups.txt updated accordingly as suggested by Li Zefan.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
This commit is contained in:
Tejun Heo 2013-11-22 18:20:44 -05:00
parent 59b6f87344
commit 3bc942f372
2 changed files with 37 additions and 40 deletions
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20
Documentation/cgroups/cgroups.txt
View File

@ -24,7 +24,6 @@ CONTENTS:
2.1 Basic Usage
2.2 Attaching processes
2.3 Mounting hierarchies by name
2.4 Notification API
3. Kernel API
3.1 Overview
3.2 Synchronization
@ -472,25 +471,6 @@ you give a subsystem a name.
The name of the subsystem appears as part of the hierarchy description
in /proc/mounts and /proc/<pid>/cgroups.
2.4 Notification API
--------------------
There is mechanism which allows to get notifications about changing
status of a cgroup.
To register a new notification handler you need to:
- create a file descriptor for event notification using eventfd(2);
- open a control file to be monitored (e.g. memory.usage_in_bytes);
- write "<event_fd> <control_fd> <args>" to cgroup.event_control.
Interpretation of args is defined by control file implementation;
eventfd will be woken up by control file implementation or when the
cgroup is removed.
To unregister a notification handler just close eventfd.
NOTE: Support of notifications should be implemented for the control
file. See documentation for the subsystem.
3. Kernel API
=============

57
mm/memcontrol.c
View File

@ -231,7 +231,7 @@ struct mem_cgroup_eventfd_list {
/*
* cgroup_event represents events which userspace want to receive.
*/
struct cgroup_event {
struct mem_cgroup_event {
/*
* memcg which the event belongs to.
*/
@ -6001,15 +6001,28 @@ static void kmem_cgroup_css_offline(struct mem_cgroup *memcg)
}
#endif
/*
* DO NOT USE IN NEW FILES.
*
* "cgroup.event_control" implementation.
*
* This is way over-engineered. It tries to support fully configurable
* events for each user. Such level of flexibility is completely
* unnecessary especially in the light of the planned unified hierarchy.
*
* Please deprecate this and replace with something simpler if at all
* possible.
*/
/*
* Unregister event and free resources.
*
* Gets called from workqueue.
*/
static void cgroup_event_remove(struct work_struct *work)
static void memcg_event_remove(struct work_struct *work)
{
struct cgroup_event *event = container_of(work, struct cgroup_event,
remove);
struct mem_cgroup_event *event =
container_of(work, struct mem_cgroup_event, remove);
struct mem_cgroup *memcg = event->memcg;
remove_wait_queue(event->wqh, &event->wait);
@ -6029,11 +6042,11 @@ static void cgroup_event_remove(struct work_struct *work)
*
* Called with wqh->lock held and interrupts disabled.
*/
static int cgroup_event_wake(wait_queue_t *wait, unsigned mode,
int sync, void *key)
static int memcg_event_wake(wait_queue_t *wait, unsigned mode,
int sync, void *key)
{
struct cgroup_event *event = container_of(wait,
struct cgroup_event, wait);
struct mem_cgroup_event *event =
container_of(wait, struct mem_cgroup_event, wait);
struct mem_cgroup *memcg = event->memcg;
unsigned long flags = (unsigned long)key;
@ -6062,27 +6075,29 @@ static int cgroup_event_wake(wait_queue_t *wait, unsigned mode,
return 0;
}
static void cgroup_event_ptable_queue_proc(struct file *file,
static void memcg_event_ptable_queue_proc(struct file *file,
wait_queue_head_t *wqh, poll_table *pt)
{
struct cgroup_event *event = container_of(pt,
struct cgroup_event, pt);
struct mem_cgroup_event *event =
container_of(pt, struct mem_cgroup_event, pt);
event->wqh = wqh;
add_wait_queue(wqh, &event->wait);
}
/*
* DO NOT USE IN NEW FILES.
*
* Parse input and register new cgroup event handler.
*
* Input must be in format '<event_fd> <control_fd> <args>'.
* Interpretation of args is defined by control file implementation.
*/
static int cgroup_write_event_control(struct cgroup_subsys_state *css,
struct cftype *cft, const char *buffer)
static int memcg_write_event_control(struct cgroup_subsys_state *css,
struct cftype *cft, const char *buffer)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct cgroup_event *event;
struct mem_cgroup_event *event;
struct cgroup_subsys_state *cfile_css;
unsigned int efd, cfd;
struct fd efile;
@ -6107,9 +6122,9 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *css,
event->memcg = memcg;
INIT_LIST_HEAD(&event->list);
init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc);
init_waitqueue_func_entry(&event->wait, cgroup_event_wake);
INIT_WORK(&event->remove, cgroup_event_remove);
init_poll_funcptr(&event->pt, memcg_event_ptable_queue_proc);
init_waitqueue_func_entry(&event->wait, memcg_event_wake);
INIT_WORK(&event->remove, memcg_event_remove);
efile = fdget(efd);
if (!efile.file) {
@ -6140,6 +6155,8 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *css,
* to be done via struct cftype but cgroup core no longer knows
* about these events. The following is crude but the whole thing
* is for compatibility anyway.
*
* DO NOT ADD NEW FILES.
*/
name = cfile.file->f_dentry->d_name.name;
@ -6251,8 +6268,8 @@ static struct cftype mem_cgroup_files[] = {
.read_u64 = mem_cgroup_hierarchy_read,
},
{
.name = "cgroup.event_control",
.write_string = cgroup_write_event_control,
.name = "cgroup.event_control", /* XXX: for compat */
.write_string = memcg_write_event_control,
.flags = CFTYPE_NO_PREFIX,
.mode = S_IWUGO,
},
@ -6585,7 +6602,7 @@ static void mem_cgroup_invalidate_reclaim_iterators(struct mem_cgroup *memcg)
static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);
struct cgroup_event *event, *tmp;
struct mem_cgroup_event *event, *tmp;
/*
* Unregister events and notify userspace.