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cgroup: kill subsys->can_attach_task(), pre_attach() and attach_task()

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These three methods are no longer used.  Kill them.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Paul Menage <paul@paulmenage.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
This commit is contained in:
Tejun Heo 2011-12-12 18:12:22 -08:00
parent 94196f51c1
commit 494c167cf7
3 changed files with 5 additions and 70 deletions
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20
Documentation/cgroups/cgroups.txt
View File

@ -615,13 +615,6 @@ fork. If this method returns 0 (success) then this should remain valid
while the caller holds cgroup_mutex and it is ensured that either
attach() or cancel_attach() will be called in future.
int can_attach_task(struct cgroup *cgrp, struct task_struct *tsk);
(cgroup_mutex held by caller)
As can_attach, but for operations that must be run once per task to be
attached (possibly many when using cgroup_attach_proc). Called after
can_attach.
void cancel_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup_taskset *tset)
(cgroup_mutex held by caller)
@ -632,12 +625,6 @@ function, so that the subsystem can implement a rollback. If not, not necessary.
This will be called only about subsystems whose can_attach() operation have
succeeded. The parameters are identical to can_attach().
void pre_attach(struct cgroup *cgrp);
(cgroup_mutex held by caller)
For any non-per-thread attachment work that needs to happen before
attach_task. Needed by cpuset.
void attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup_taskset *tset)
(cgroup_mutex held by caller)
@ -646,13 +633,6 @@ Called after the task has been attached to the cgroup, to allow any
post-attachment activity that requires memory allocations or blocking.
The parameters are identical to can_attach().
void attach_task(struct cgroup *cgrp, struct task_struct *tsk);
(cgroup_mutex held by caller)
As attach, but for operations that must be run once per task to be attached,
like can_attach_task. Called before attach. Currently does not support any
subsystem that might need the old_cgrp for every thread in the group.
void fork(struct cgroup_subsy *ss, struct task_struct *task)
Called when a task is forked into a cgroup.

3
include/linux/cgroup.h
View File

@ -490,11 +490,8 @@ struct cgroup_subsys {
void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
int (*can_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup_taskset *tset);
int (*can_attach_task)(struct cgroup *cgrp, struct task_struct *tsk);
void (*cancel_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup_taskset *tset);
void (*pre_attach)(struct cgroup *cgrp);
void (*attach_task)(struct cgroup *cgrp, struct task_struct *tsk);
void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup_taskset *tset);
void (*fork)(struct cgroup_subsys *ss, struct task_struct *task);

52
kernel/cgroup.c
View File

@ -1944,13 +1944,6 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
goto out;
}
}
if (ss->can_attach_task) {
retval = ss->can_attach_task(cgrp, tsk);
if (retval) {
failed_ss = ss;
goto out;
}
}
}
retval = cgroup_task_migrate(cgrp, oldcgrp, tsk, false);
@ -1958,10 +1951,6 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
goto out;
for_each_subsys(root, ss) {
if (ss->pre_attach)
ss->pre_attach(cgrp);
if (ss->attach_task)
ss->attach_task(cgrp, tsk);
if (ss->attach)
ss->attach(ss, cgrp, &tset);
}
@ -2093,7 +2082,6 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
{
int retval, i, group_size, nr_migrating_tasks;
struct cgroup_subsys *ss, *failed_ss = NULL;
bool cancel_failed_ss = false;
/* guaranteed to be initialized later, but the compiler needs this */
struct css_set *oldcg;
struct cgroupfs_root *root = cgrp->root;
@ -2188,21 +2176,6 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
goto out_cancel_attach;
}
}
/* a callback to be run on every thread in the threadgroup. */
if (ss->can_attach_task) {
/* run on each task in the threadgroup. */
for (i = 0; i < group_size; i++) {
tc = flex_array_get(group, i);
if (tc->cgrp == cgrp)
continue;
retval = ss->can_attach_task(cgrp, tc->task);
if (retval) {
failed_ss = ss;
cancel_failed_ss = true;
goto out_cancel_attach;
}
}
}
}
/*
@ -2234,15 +2207,10 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
}
/*
* step 3: now that we're guaranteed success wrt the css_sets, proceed
* to move all tasks to the new cgroup, calling ss->attach_task for each
* one along the way. there are no failure cases after here, so this is
* the commit point.
* step 3: now that we're guaranteed success wrt the css_sets,
* proceed to move all tasks to the new cgroup. There are no
* failure cases after here, so this is the commit point.
*/
for_each_subsys(root, ss) {
if (ss->pre_attach)
ss->pre_attach(cgrp);
}
for (i = 0; i < group_size; i++) {
tc = flex_array_get(group, i);
/* leave current thread as it is if it's already there */
@ -2250,18 +2218,11 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
continue;
retval = cgroup_task_migrate(cgrp, tc->cgrp, tc->task, true);
BUG_ON(retval);
/* attach each task to each subsystem */
for_each_subsys(root, ss) {
if (ss->attach_task)
ss->attach_task(cgrp, tc->task);
}
}
/* nothing is sensitive to fork() after this point. */
/*
* step 4: do expensive, non-thread-specific subsystem callbacks.
* TODO: if ever a subsystem needs to know the oldcgrp for each task
* being moved, this call will need to be reworked to communicate that.
* step 4: do subsystem attach callbacks.
*/
for_each_subsys(root, ss) {
if (ss->attach)
@ -2285,11 +2246,8 @@ out_cancel_attach:
/* same deal as in cgroup_attach_task */
if (retval) {
for_each_subsys(root, ss) {
if (ss == failed_ss) {
if (cancel_failed_ss && ss->cancel_attach)
ss->cancel_attach(ss, cgrp, &tset);
if (ss == failed_ss)
break;
}
if (ss->cancel_attach)
ss->cancel_attach(ss, cgrp, &tset);
}