Commit f0a0bd3d authored by Waiman Long's avatar Waiman Long Committed by Tejun Heo
Browse files

cgroup/cpuset: Code cleanup and comment update 



Rename partition_xcpus_newstate() to isolated_cpus_update(),
update_partition_exclusive() to update_partition_exclusive_flag() and
the new_xcpus_state variable to isolcpus_updated to make their meanings
more explicit. Also add some comments to further clarify the code.
No functional change is expected.

Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 6da580ec

kernel/cgroup/cpuset.c

+38 −23
Original line number Diff line number Diff line
@@ -65,7 +65,13 @@ static const char * const perr_strings[] = { 
};



/*

 * Exclusive CPUs distributed out to sub-partitions of top_cpuset

 * For local partitions, update to subpartitions_cpus & isolated_cpus is done

 * in update_parent_effective_cpumask(). For remote partitions, it is done in

 * the remote_partition_*() and remote_cpus_update() helpers.

 */

/*

 * Exclusive CPUs distributed out to local or remote sub-partitions of

 * top_cpuset

 */

static cpumask_var_t	subpartitions_cpus;
@@ -1089,9 +1095,14 @@ void cpuset_reset_sched_domains(void) 
 *

 * Iterate through each task of @cs updating its cpus_allowed to the

 * effective cpuset's.  As this function is called with cpuset_mutex held,

 * cpuset membership stays stable. For top_cpuset, task_cpu_possible_mask()

 * is used instead of effective_cpus to make sure all offline CPUs are also

 * included as hotplug code won't update cpumasks for tasks in top_cpuset.

 * cpuset membership stays stable.

 *

 * For top_cpuset, task_cpu_possible_mask() is used instead of effective_cpus

 * to make sure all offline CPUs are also included as hotplug code won't

 * update cpumasks for tasks in top_cpuset.

 *

 * As task_cpu_possible_mask() can be task dependent in arm64, we have to

 * do cpu masking per task instead of doing it once for all.

 */

void cpuset_update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus)

{
@@ -1151,7 +1162,7 @@ static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs, 
 *

 * Return: 0 if successful, an error code otherwise

 */

static int update_partition_exclusive(struct cpuset *cs, int new_prs)

static int update_partition_exclusive_flag(struct cpuset *cs, int new_prs)

{

	bool exclusive = (new_prs > PRS_MEMBER);
@@ -1234,12 +1245,12 @@ static void reset_partition_data(struct cpuset *cs) 
}



/*

 * partition_xcpus_newstate - Exclusive CPUs state change

 * isolated_cpus_update - Update the isolated_cpus mask

 * @old_prs: old partition_root_state

 * @new_prs: new partition_root_state

 * @xcpus: exclusive CPUs with state change

 */

static void partition_xcpus_newstate(int old_prs, int new_prs, struct cpumask *xcpus)

static void isolated_cpus_update(int old_prs, int new_prs, struct cpumask *xcpus)

{

	WARN_ON_ONCE(old_prs == new_prs);

	if (new_prs == PRS_ISOLATED)
@@ -1273,7 +1284,7 @@ static bool partition_xcpus_add(int new_prs, struct cpuset *parent, 


	isolcpus_updated = (new_prs != parent->partition_root_state);

	if (isolcpus_updated)

		partition_xcpus_newstate(parent->partition_root_state, new_prs,

		isolated_cpus_update(parent->partition_root_state, new_prs,

				     xcpus);



	cpumask_andnot(parent->effective_cpus, parent->effective_cpus, xcpus);
@@ -1304,7 +1315,7 @@ static bool partition_xcpus_del(int old_prs, struct cpuset *parent, 


	isolcpus_updated = (old_prs != parent->partition_root_state);

	if (isolcpus_updated)

		partition_xcpus_newstate(old_prs, parent->partition_root_state,

		isolated_cpus_update(old_prs, parent->partition_root_state,

				     xcpus);



	cpumask_and(xcpus, xcpus, cpu_active_mask);
@@ -1634,8 +1645,8 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, 
	int old_prs, new_prs;

	int part_error = PERR_NONE;	/* Partition error? */

	int subparts_delta = 0;

	struct cpumask *xcpus;		/* cs effective_xcpus */

	int isolcpus_updated = 0;

	struct cpumask *xcpus = user_xcpus(cs);

	bool nocpu;



	lockdep_assert_held(&cpuset_mutex);
@@ -1647,7 +1658,6 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, 
	 */

	adding = deleting = false;

	old_prs = new_prs = cs->partition_root_state;

	xcpus = user_xcpus(cs);



	if (cmd == partcmd_invalidate) {

		if (is_prs_invalid(old_prs))
@@ -1861,7 +1871,7 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, 
	 * CPU lists in cs haven't been updated yet. So defer it to later.

	 */

	if ((old_prs != new_prs) && (cmd != partcmd_update))  {

		int err = update_partition_exclusive(cs, new_prs);

		int err = update_partition_exclusive_flag(cs, new_prs);



		if (err)

			return err;
@@ -1899,7 +1909,7 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, 
	update_unbound_workqueue_cpumask(isolcpus_updated);



	if ((old_prs != new_prs) && (cmd == partcmd_update))

		update_partition_exclusive(cs, new_prs);

		update_partition_exclusive_flag(cs, new_prs);



	if (adding || deleting) {

		cpuset_update_tasks_cpumask(parent, tmp->addmask);
@@ -2829,7 +2839,7 @@ static int update_prstate(struct cpuset *cs, int new_prs) 
	int err = PERR_NONE, old_prs = cs->partition_root_state;

	struct cpuset *parent = parent_cs(cs);

	struct tmpmasks tmpmask;

	bool new_xcpus_state = false;

	bool isolcpus_updated = false;



	if (old_prs == new_prs)

		return 0;
@@ -2843,7 +2853,7 @@ static int update_prstate(struct cpuset *cs, int new_prs) 
	if (alloc_cpumasks(NULL, &tmpmask))

		return -ENOMEM;



	err = update_partition_exclusive(cs, new_prs);

	err = update_partition_exclusive_flag(cs, new_prs);

	if (err)

		goto out;
@@ -2884,8 +2894,9 @@ static int update_prstate(struct cpuset *cs, int new_prs) 
	} else if (old_prs && new_prs) {

		/*

		 * A change in load balance state only, no change in cpumasks.

		 * Need to update isolated_cpus.

		 */

		new_xcpus_state = true;

		isolcpus_updated = true;

	} else {

		/*

		 * Switching back to member is always allowed even if it
@@ -2909,7 +2920,7 @@ static int update_prstate(struct cpuset *cs, int new_prs) 
	 */

	if (err) {

		new_prs = -new_prs;

		update_partition_exclusive(cs, new_prs);

		update_partition_exclusive_flag(cs, new_prs);

	}



	spin_lock_irq(&callback_lock);
@@ -2917,14 +2928,18 @@ static int update_prstate(struct cpuset *cs, int new_prs) 
	WRITE_ONCE(cs->prs_err, err);

	if (!is_partition_valid(cs))

		reset_partition_data(cs);

	else if (new_xcpus_state)

		partition_xcpus_newstate(old_prs, new_prs, cs->effective_xcpus);

	else if (isolcpus_updated)

		isolated_cpus_update(old_prs, new_prs, cs->effective_xcpus);

	spin_unlock_irq(&callback_lock);

	update_unbound_workqueue_cpumask(new_xcpus_state);

	update_unbound_workqueue_cpumask(isolcpus_updated);



	/* Force update if switching back to member */

	/* Force update if switching back to member & update effective_xcpus */

	update_cpumasks_hier(cs, &tmpmask, !new_prs);



	/* A newly created partition must have effective_xcpus set */

	WARN_ON_ONCE(!old_prs && (new_prs > 0)

			      && cpumask_empty(cs->effective_xcpus));



	/* Update sched domains and load balance flag */

	update_partition_sd_lb(cs, old_prs);