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cgroup: don't use subsys->can_attach_task() or ->attach_task()

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Now that subsys->can_attach() and attach() take @tset instead of
@task, they can handle per-task operations.  Convert
->can_attach_task() and ->attach_task() users to use ->can_attach()
and attach() instead.  Most converions are straight-forward.
Noteworthy changes are,

* In cgroup_freezer, remove unnecessary NULL assignments to unused
  methods.  It's useless and very prone to get out of sync, which
  already happened.

* In cpuset, PF_THREAD_BOUND test is checked for each task.  This
  doesn't make any practical difference but is conceptually cleaner.

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: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <paul@paulmenage.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: James Morris <jmorris@namei.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
This commit is contained in:
Tejun Heo 2011-12-12 18:12:21 -08:00
parent 2f7ee5691e
commit bb9d97b6df
5 changed files with 91 additions and 82 deletions
Download patch file Download diff file Expand all files Collapse all files

70
kernel/cpuset.c
View file

@ -1375,33 +1375,34 @@ static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup_taskset *tset)
{
struct cpuset *cs = cgroup_cs(cgrp);
struct task_struct *task;
int ret;
if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
return -ENOSPC;
/*
* Kthreads bound to specific cpus cannot be moved to a new cpuset; we
* cannot change their cpu affinity and isolating such threads by their
* set of allowed nodes is unnecessary. Thus, cpusets are not
* applicable for such threads. This prevents checking for success of
* set_cpus_allowed_ptr() on all attached tasks before cpus_allowed may
* be changed.
*/
if (cgroup_taskset_first(tset)->flags & PF_THREAD_BOUND)
return -EINVAL;
cgroup_taskset_for_each(task, cgrp, tset) {
/*
* Kthreads bound to specific cpus cannot be moved to a new
* cpuset; we cannot change their cpu affinity and
* isolating such threads by their set of allowed nodes is
* unnecessary. Thus, cpusets are not applicable for such
* threads. This prevents checking for success of
* set_cpus_allowed_ptr() on all attached tasks before
* cpus_allowed may be changed.
*/
if (task->flags & PF_THREAD_BOUND)
return -EINVAL;
if ((ret = security_task_setscheduler(task)))
return ret;
}
return 0;
}
static int cpuset_can_attach_task(struct cgroup *cgrp, struct task_struct *task)
{
return security_task_setscheduler(task);
}
/*
* Protected by cgroup_lock. The nodemasks must be stored globally because
* dynamically allocating them is not allowed in pre_attach, and they must
* persist among pre_attach, attach_task, and attach.
* persist among pre_attach, and attach.
*/
static cpumask_var_t cpus_attach;
static nodemask_t cpuset_attach_nodemask_from;
@ -1420,39 +1421,34 @@ static void cpuset_pre_attach(struct cgroup *cont)
guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
}
/* Per-thread attachment work. */
static void cpuset_attach_task(struct cgroup *cont, struct task_struct *tsk)
{
int err;
struct cpuset *cs = cgroup_cs(cont);
/*
* can_attach beforehand should guarantee that this doesn't fail.
* TODO: have a better way to handle failure here
*/
err = set_cpus_allowed_ptr(tsk, cpus_attach);
WARN_ON_ONCE(err);
cpuset_change_task_nodemask(tsk, &cpuset_attach_nodemask_to);
cpuset_update_task_spread_flag(cs, tsk);
}
static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup_taskset *tset)
{
struct mm_struct *mm;
struct task_struct *tsk = cgroup_taskset_first(tset);
struct task_struct *task;
struct task_struct *leader = cgroup_taskset_first(tset);
struct cgroup *oldcgrp = cgroup_taskset_cur_cgroup(tset);
struct cpuset *cs = cgroup_cs(cgrp);
struct cpuset *oldcs = cgroup_cs(oldcgrp);
cgroup_taskset_for_each(task, cgrp, tset) {
/*
* can_attach beforehand should guarantee that this doesn't
* fail. TODO: have a better way to handle failure here
*/
WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpus_attach));
cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to);
cpuset_update_task_spread_flag(cs, task);
}
/*
* Change mm, possibly for multiple threads in a threadgroup. This is
* expensive and may sleep.
*/
cpuset_attach_nodemask_from = oldcs->mems_allowed;
cpuset_attach_nodemask_to = cs->mems_allowed;
mm = get_task_mm(tsk);
mm = get_task_mm(leader);
if (mm) {
mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
if (is_memory_migrate(cs))
@ -1908,9 +1904,7 @@ struct cgroup_subsys cpuset_subsys = {
.create = cpuset_create,
.destroy = cpuset_destroy,
.can_attach = cpuset_can_attach,
.can_attach_task = cpuset_can_attach_task,
.pre_attach = cpuset_pre_attach,
.attach_task = cpuset_attach_task,
.attach = cpuset_attach,
.populate = cpuset_populate,
.post_clone = cpuset_post_clone,