Commit aecd408b authored by Yafang Shao's avatar Yafang Shao Committed by Tejun Heo
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cgroup: Add a new helper for cgroup1 hierarchy 



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: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarYafang Shao <laoar.shao@gmail.com>
Cc: Hou Tao <houtao@huaweicloud.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 0008454e

include/linux/cgroup.h

+3 −1
Original line number Diff line number Diff line
@@ -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 */

kernel/cgroup/cgroup-internal.h

+0 −1
Original line number Diff line number Diff line
@@ -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;

kernel/cgroup/cgroup-v1.c

+34 −0
Original line number Diff line number Diff line
@@ -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)

{

	/*