Commit 4e4c9a14 authored by Tejun Heo's avatar Tejun Heo
Browse files

cpuset: cleanup cpuset[_can]_attach() 



cpuset_can_attach() prepare global variables cpus_attach and
cpuset_attach_nodemask_{to|from} which are used by cpuset_attach().
There is no reason to prepare in cpuset_can_attach().  The same
information can be accessed from cpuset_attach().

Move the prepartion logic from cpuset_can_attach() to cpuset_attach()
and make the global variables static ones inside cpuset_attach().

With this change, there's no reason to keep
cpuset_attach_nodemask_{from|to} global.  Move them inside
cpuset_attach().  Unfortunately, we need to keep cpus_attach global as
it can't be allocated from cpuset_attach().

v2: cpus_attach not converted to cpumask_t as per Li Zefan and Rusty
    Russell.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
parent ae8086ce

kernel/cpuset.c

+18 −17
Original line number Diff line number Diff line
@@ -1395,15 +1395,6 @@ static int fmeter_getrate(struct fmeter *fmp) 
	return val;

}



/*

 * Protected by cgroup_lock. The nodemasks must be stored globally because

 * dynamically allocating them is not allowed in can_attach, and they must

 * persist until attach.

 */

static cpumask_var_t cpus_attach;

static nodemask_t cpuset_attach_nodemask_from;

static nodemask_t cpuset_attach_nodemask_to;



/* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */

static int cpuset_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)

{
@@ -1430,19 +1421,21 @@ static int cpuset_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset) 
			return ret;

	}



	/* prepare for attach */

	if (cs == &top_cpuset)

		cpumask_copy(cpus_attach, cpu_possible_mask);

	else

		guarantee_online_cpus(cs, cpus_attach);



	guarantee_online_mems(cs, &cpuset_attach_nodemask_to);



	return 0;

}



/*

 * Protected by cgroup_mutex.  cpus_attach is used only by cpuset_attach()

 * but we can't allocate it dynamically there.  Define it global and

 * allocate from cpuset_init().

 */

static cpumask_var_t cpus_attach;



static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)

{

	/* static bufs protected by cgroup_mutex */

	static nodemask_t cpuset_attach_nodemask_from;

	static nodemask_t cpuset_attach_nodemask_to;

	struct mm_struct *mm;

	struct task_struct *task;

	struct task_struct *leader = cgroup_taskset_first(tset);
@@ -1450,6 +1443,14 @@ static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset) 
	struct cpuset *cs = cgroup_cs(cgrp);

	struct cpuset *oldcs = cgroup_cs(oldcgrp);



	/* prepare for attach */

	if (cs == &top_cpuset)

		cpumask_copy(cpus_attach, cpu_possible_mask);

	else

		guarantee_online_cpus(cs, cpus_attach);



	guarantee_online_mems(cs, &cpuset_attach_nodemask_to);



	cgroup_taskset_for_each(task, cgrp, tset) {

		/*

		 * can_attach beforehand should guarantee that this doesn't

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