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cgroup/cpuset: Code cleanup and comment update 

JIRA: https://issues.redhat.com/browse/RHEL-83455
Conflicts: Some minor context diffs due to missing upstream commit
	   381b53c3b549 ("cgroup/cpuset: rename functions shared
	   between v1 and v2") and commit 2ff899e35164 ("sched/deadline:
	   Rebuild root domain accounting after every update").

commit f0a0bd3d23a44a2c5f628e8ca8ad882498ca5aae
Author: Waiman Long <longman@redhat.com>
Date:   Sun, 30 Mar 2025 17:52:44 -0400

    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: Waiman Long <longman@redhat.com>
    Signed-off-by: Tejun Heo <tj@kernel.org>

Signed-off-by: Waiman Long <longman@redhat.com>
This commit is contained in:
Waiman Long 2025-04-09 21:58:41 -04:00
parent 710ee1a4b8
commit 19950eb6cd
1 changed files with 38 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

61
kernel/cgroup/cpuset.c
View File

@ -215,7 +215,13 @@ struct cpuset_remove_tasks_struct {
};
/*
* 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;
@ -1359,9 +1365,14 @@ void rebuild_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.
*/
static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus)
{
@ -1423,7 +1434,7 @@ 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);
@ -1506,12 +1517,12 @@ 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)
@ -1545,8 +1556,8 @@ 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,
xcpus);
isolated_cpus_update(parent->partition_root_state, new_prs,
xcpus);
cpumask_andnot(parent->effective_cpus, parent->effective_cpus, xcpus);
return isolcpus_updated;
@ -1576,8 +1587,8 @@ 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,
xcpus);
isolated_cpus_update(old_prs, parent->partition_root_state,
xcpus);
cpumask_and(xcpus, xcpus, cpu_active_mask);
cpumask_or(parent->effective_cpus, parent->effective_cpus, xcpus);
@ -1906,8 +1917,8 @@ 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);
@ -1919,7 +1930,6 @@ 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))
@ -2133,7 +2143,7 @@ write_error:
* 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;
@ -2171,7 +2181,7 @@ write_error:
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) {
update_tasks_cpumask(parent, tmp->addmask);
@ -3140,7 +3150,7 @@ 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;
@ -3154,7 +3164,7 @@ 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;
@ -3182,8 +3192,9 @@ 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
@ -3207,7 +3218,7 @@ out:
*/
if (err) {
new_prs = -new_prs;
update_partition_exclusive(cs, new_prs);
update_partition_exclusive_flag(cs, new_prs);
}
spin_lock_irq(&callback_lock);
@ -3215,14 +3226,18 @@ out:
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);