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cgroup: Add a new helper for cgroup1 hierarchy

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A new helper is added for cgroup1 hierarchy:

- task_get_cgroup1
  Acquires the associated cgroup of a task within a specific cgroup1
  hierarchy. The cgroup1 hierarchy is identified by its hierarchy ID.

This helper function is added to facilitate the tracing of tasks within
a particular container or cgroup dir in BPF programs. It's important to
note that this helper is designed specifically for cgroup1 only.

tj: Use irsqsave/restore as suggested by Hou Tao <houtao@huaweicloud.com>.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Hou Tao <houtao@huaweicloud.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Yafang Shao 2023-10-29 06:14:32 +00:00 committed by Tejun Heo
parent 0008454e8f
commit aecd408b7e
3 changed files with 37 additions and 2 deletions
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4
include/linux/cgroup.h
View file

@ -69,6 +69,7 @@ struct css_task_iter {
extern struct file_system_type cgroup_fs_type;
extern struct cgroup_root cgrp_dfl_root;
extern struct css_set init_css_set;
extern spinlock_t css_set_lock;
#define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;
#include <linux/cgroup_subsys.h>
@ -386,7 +387,6 @@ static inline void cgroup_unlock(void)
* as locks used during the cgroup_subsys::attach() methods.
*/
#ifdef CONFIG_PROVE_RCU
extern spinlock_t css_set_lock;
#define task_css_set_check(task, __c) \
rcu_dereference_check((task)->cgroups, \
rcu_read_lock_sched_held() || \
@ -853,4 +853,6 @@ static inline void cgroup_bpf_put(struct cgroup *cgrp) {}
#endif /* CONFIG_CGROUP_BPF */
struct cgroup *task_get_cgroup1(struct task_struct *tsk, int hierarchy_id);
#endif /* _LINUX_CGROUP_H */

1
kernel/cgroup/cgroup-internal.h
View file

@ -164,7 +164,6 @@ struct cgroup_mgctx {
#define DEFINE_CGROUP_MGCTX(name) \
struct cgroup_mgctx name = CGROUP_MGCTX_INIT(name)
extern spinlock_t css_set_lock;
extern struct cgroup_subsys *cgroup_subsys[];
extern struct list_head cgroup_roots;

34
kernel/cgroup/cgroup-v1.c
View file

@ -1262,6 +1262,40 @@ int cgroup1_get_tree(struct fs_context *fc)
return ret;
}
/**
* task_get_cgroup1 - Acquires the associated cgroup of a task within a
* specific cgroup1 hierarchy. The cgroup1 hierarchy is identified by its
* hierarchy ID.
* @tsk: The target task
* @hierarchy_id: The ID of a cgroup1 hierarchy
*
* On success, the cgroup is returned. On failure, ERR_PTR is returned.
* We limit it to cgroup1 only.
*/
struct cgroup *task_get_cgroup1(struct task_struct *tsk, int hierarchy_id)
{
struct cgroup *cgrp = ERR_PTR(-ENOENT);
struct cgroup_root *root;
unsigned long flags;
rcu_read_lock();
for_each_root(root) {
/* cgroup1 only*/
if (root == &cgrp_dfl_root)
continue;
if (root->hierarchy_id != hierarchy_id)
continue;
spin_lock_irqsave(&css_set_lock, flags);
cgrp = task_cgroup_from_root(tsk, root);
if (!cgrp || !cgroup_tryget(cgrp))
cgrp = ERR_PTR(-ENOENT);
spin_unlock_irqrestore(&css_set_lock, flags);
break;
}
rcu_read_unlock();
return cgrp;
}
static int __init cgroup1_wq_init(void)
{
/*