Commit bb9d97b6 authored by Tejun Heo's avatar Tejun Heo

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

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: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: default avatarLi 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>
parent 2f7ee569
......@@ -30,8 +30,10 @@ EXPORT_SYMBOL_GPL(blkio_root_cgroup);
static struct cgroup_subsys_state *blkiocg_create(struct cgroup_subsys *,
struct cgroup *);
static int blkiocg_can_attach_task(struct cgroup *, struct task_struct *);
static void blkiocg_attach_task(struct cgroup *, struct task_struct *);
static int blkiocg_can_attach(struct cgroup_subsys *, struct cgroup *,
struct cgroup_taskset *);
static void blkiocg_attach(struct cgroup_subsys *, struct cgroup *,
struct cgroup_taskset *);
static void blkiocg_destroy(struct cgroup_subsys *, struct cgroup *);
static int blkiocg_populate(struct cgroup_subsys *, struct cgroup *);
......@@ -44,8 +46,8 @@ static int blkiocg_populate(struct cgroup_subsys *, struct cgroup *);
struct cgroup_subsys blkio_subsys = {
.name = "blkio",
.create = blkiocg_create,
.can_attach_task = blkiocg_can_attach_task,
.attach_task = blkiocg_attach_task,
.can_attach = blkiocg_can_attach,
.attach = blkiocg_attach,
.destroy = blkiocg_destroy,
.populate = blkiocg_populate,
#ifdef CONFIG_BLK_CGROUP
......@@ -1626,30 +1628,39 @@ blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
* of the main cic data structures. For now we allow a task to change
* its cgroup only if it's the only owner of its ioc.
*/
static int blkiocg_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
static int blkiocg_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup_taskset *tset)
{
struct task_struct *task;
struct io_context *ioc;
int ret = 0;
/* task_lock() is needed to avoid races with exit_io_context() */
task_lock(tsk);
ioc = tsk->io_context;
cgroup_taskset_for_each(task, cgrp, tset) {
task_lock(task);
ioc = task->io_context;
if (ioc && atomic_read(&ioc->nr_tasks) > 1)
ret = -EINVAL;
task_unlock(tsk);
task_unlock(task);
if (ret)
break;
}
return ret;
}
static void blkiocg_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
static void blkiocg_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup_taskset *tset)
{
struct task_struct *task;
struct io_context *ioc;
task_lock(tsk);
ioc = tsk->io_context;
cgroup_taskset_for_each(task, cgrp, tset) {
task_lock(task);
ioc = task->io_context;
if (ioc)
ioc->cgroup_changed = 1;
task_unlock(tsk);
task_unlock(task);
}
}
void blkio_policy_register(struct blkio_policy_type *blkiop)
......
......@@ -162,10 +162,14 @@ static int freezer_can_attach(struct cgroup_subsys *ss,
struct cgroup_taskset *tset)
{
struct freezer *freezer;
struct task_struct *task;
/*
* Anything frozen can't move or be moved to/from.
*/
cgroup_taskset_for_each(task, new_cgroup, tset)
if (cgroup_freezing(task))
return -EBUSY;
freezer = cgroup_freezer(new_cgroup);
if (freezer->state != CGROUP_THAWED)
......@@ -174,11 +178,6 @@ static int freezer_can_attach(struct cgroup_subsys *ss,
return 0;
}
static int freezer_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
{
return cgroup_freezing(tsk) ? -EBUSY : 0;
}
static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task)
{
struct freezer *freezer;
......@@ -374,10 +373,5 @@ struct cgroup_subsys freezer_subsys = {
.populate = freezer_populate,
.subsys_id = freezer_subsys_id,
.can_attach = freezer_can_attach,
.can_attach_task = freezer_can_attach_task,
.pre_attach = NULL,
.attach_task = NULL,
.attach = NULL,
.fork = freezer_fork,
.exit = NULL,
};
......@@ -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;
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 (cgroup_taskset_first(tset)->flags & PF_THREAD_BOUND)
* 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,
......
......@@ -7044,9 +7044,12 @@ static int __perf_cgroup_move(void *info)
return 0;
}
static void
perf_cgroup_attach_task(struct cgroup *cgrp, struct task_struct *task)
static void perf_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup_taskset *tset)
{
struct task_struct *task;
cgroup_taskset_for_each(task, cgrp, tset)
task_function_call(task, __perf_cgroup_move, task);
}
......@@ -7061,7 +7064,7 @@ static void perf_cgroup_exit(struct cgroup_subsys *ss, struct cgroup *cgrp,
if (!(task->flags & PF_EXITING))
return;
perf_cgroup_attach_task(cgrp, task);
task_function_call(task, __perf_cgroup_move, task);
}
struct cgroup_subsys perf_subsys = {
......@@ -7070,6 +7073,6 @@ struct cgroup_subsys perf_subsys = {
.create = perf_cgroup_create,
.destroy = perf_cgroup_destroy,
.exit = perf_cgroup_exit,
.attach_task = perf_cgroup_attach_task,
.attach = perf_cgroup_attach,
};
#endif /* CONFIG_CGROUP_PERF */
......@@ -9127,24 +9127,31 @@ cpu_cgroup_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
sched_destroy_group(tg);
}
static int
cpu_cgroup_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
static int cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup_taskset *tset)
{
struct task_struct *task;
cgroup_taskset_for_each(task, cgrp, tset) {
#ifdef CONFIG_RT_GROUP_SCHED
if (!sched_rt_can_attach(cgroup_tg(cgrp), tsk))
if (!sched_rt_can_attach(cgroup_tg(cgrp), task))
return -EINVAL;
#else
/* We don't support RT-tasks being in separate groups */
if (tsk->sched_class != &fair_sched_class)
if (task->sched_class != &fair_sched_class)
return -EINVAL;
#endif
}
return 0;
}
static void
cpu_cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
static void cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup_taskset *tset)
{
sched_move_task(tsk);
struct task_struct *task;
cgroup_taskset_for_each(task, cgrp, tset)
sched_move_task(task);
}
static void
......@@ -9480,8 +9487,8 @@ struct cgroup_subsys cpu_cgroup_subsys = {
.name = "cpu",
.create = cpu_cgroup_create,
.destroy = cpu_cgroup_destroy,
.can_attach_task = cpu_cgroup_can_attach_task,
.attach_task = cpu_cgroup_attach_task,
.can_attach = cpu_cgroup_can_attach,
.attach = cpu_cgroup_attach,
.exit = cpu_cgroup_exit,
.populate = cpu_cgroup_populate,
.subsys_id = cpu_cgroup_subsys_id,
......
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