[Devel] [PATCH v10 6/9] ve/cgroup: unmark ve-root cgroups at container stop
Kirill Tkhai
ktkhai at virtuozzo.com
Fri Apr 17 15:14:19 MSK 2020
On 17.04.2020 15:11, Valeriy Vdovin wrote:
>>Will the function work correctly in case jf we completely remove above "if"? Is this "if" optimization for init_css_set?
>
> This is indeed an optimization. And also it looks like it's the most common case.
(Please, avoid top-posting in your replies. Top-posting is not welcomed. See in Documentation/development-process/2.Process)
Then, we should add a comment about that this is optimization, I think.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> *From:* Kirill Tkhai <ktkhai at virtuozzo.com>
> *Sent:* Friday, April 17, 2020 12:15 PM
> *To:* Valeriy Vdovin <Valeriy.Vdovin at virtuozzo.com>; devel at openvz.org <devel at openvz.org>; Konstantin Khorenko <khorenko at virtuozzo.com>; Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
> *Subject:* Re: [PATCH v10 6/9] ve/cgroup: unmark ve-root cgroups at container stop
>
> On 16.04.2020 19:14, Valeriy Vdovin wrote:
>> Signed-off-by: Valeriy Vdovin <valeriy.vdovin at virtuozzo.com>
>> Reviewed-by: Kirill Tkhai <ktkhai at virtuozzo.com>
>> ---
>> include/linux/cgroup.h | 1 +
>> kernel/cgroup.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>> kernel/ve/ve.c | 2 ++
>> 3 files changed, 45 insertions(+)
>>
>> diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
>> index 0a42f93..1bd0fe7 100644
>> --- a/include/linux/cgroup.h
>> +++ b/include/linux/cgroup.h
>> @@ -636,6 +636,7 @@ int cgroup_task_count(const struct cgroup *cgrp);
>>
>> #ifdef CONFIG_VE
>> void cgroup_mark_ve_roots(struct ve_struct *ve);
>> +void cgroup_unmark_ve_roots(struct ve_struct *ve);
>> #endif
>>
>> /*
>> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
>> index 60a4ca4..1dd36ed 100644
>> --- a/kernel/cgroup.c
>> +++ b/kernel/cgroup.c
>> @@ -635,6 +635,35 @@ static struct css_set *find_css_set(
>> }
>>
>> /*
>> + * Walk each cgroup link of a given css_set and find a cgroup that
>> + * is the child of cgroupfs_root in argument.
>> + */
>> +static struct cgroup *css_cgroup_from_root(struct css_set *css_set,
>> + struct cgroupfs_root *root)
>> +{
>> + struct cgroup *res = NULL;
>> +
>> + BUG_ON(!mutex_is_locked(&cgroup_mutex));
>> + read_lock(&css_set_lock);
>> +
>> + if (css_set == &init_css_set) {
>> + res = &root->top_cgroup;
>
> Will the function work correctly in case jf we completely remove above "if"?
> Is this "if" optimization for init_css_set?
>
>> + } else {
>> + struct cg_cgroup_link *link;
>> + list_for_each_entry(link, &css_set->cg_links, cg_link_list) {
>> + struct cgroup *c = link->cgrp;
>> + if (c->root == root) {
>> + res = c;
>> + break;
>> + }
>> + }
>> + }
>> + read_unlock(&css_set_lock);
>> + BUG_ON(!res);
>> + return res;
>> +}
>> +
>> +/*
>> * Return the cgroup for "task" from the given hierarchy. Must be
>> * called with cgroup_mutex held.
>> */
>> @@ -4237,6 +4266,19 @@ void cgroup_mark_ve_roots(struct ve_struct *ve)
>> mutex_unlock(&cgroup_mutex);
>> }
>>
>> +void cgroup_unmark_ve_roots(struct ve_struct *ve)
>> +{
>> + struct cgroup *cgrp;
>> + struct cgroupfs_root *root;
>> +
>> + mutex_lock(&cgroup_mutex);
>> + for_each_active_root(root) {
>> + cgrp = css_cgroup_from_root(ve->root_css_set, root);
>> + clear_bit(CGRP_VE_ROOT, &cgrp->flags);
>> + }
>> + mutex_unlock(&cgroup_mutex);
>> +}
>> +
>> struct cgroup *cgroup_get_ve_root(struct cgroup *cgrp)
>> {
>> struct cgroup *ve_root = NULL;
>> diff --git a/kernel/ve/ve.c b/kernel/ve/ve.c
>> index eedb85d..db3b600 100644
>> --- a/kernel/ve/ve.c
>> +++ b/kernel/ve/ve.c
>> @@ -618,6 +618,8 @@ void ve_exit_ns(struct pid_namespace *pid_ns)
>> if (!ve->ve_ns || ve->ve_ns->pid_ns != pid_ns)
>> return;
>>
>> + cgroup_unmark_ve_roots(ve);
>> +
>> ve_workqueue_stop(ve);
>>
>> /*
>>
>
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