Commit 6b658c48 authored by Muneendra Kumar's avatar Muneendra Kumar Committed by Martin K. Petersen
Browse files

scsi: cgroup: Add cgroup_get_from_id() 

Add a new function, cgroup_get_from_id(), to retrieve the cgroup associated
with a cgroup id. Also export the function cgroup_get_e_css() as this is
needed in blk-cgroup.h.

Link: https://lore.kernel.org/r/20210608043556.274139-2-muneendra.kumar@broadcom.com


Reviewed-by: default avatarHimanshu Madhani <himanshu.madhani@oracle.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarMuneendra Kumar <muneendra.kumar@broadcom.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 49d3e599

include/linux/cgroup.h

+6 −0
Original line number Diff line number Diff line
@@ -696,6 +696,7 @@ static inline void cgroup_kthread_ready(void) 
}



void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen);

struct cgroup *cgroup_get_from_id(u64 id);

#else /* !CONFIG_CGROUPS */



struct cgroup_subsys_state;
@@ -743,6 +744,11 @@ static inline bool task_under_cgroup_hierarchy(struct task_struct *task, 


static inline void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen)

{}



static inline struct cgroup *cgroup_get_from_id(u64 id)

{

	return NULL;

}

#endif /* !CONFIG_CGROUPS */



#ifdef CONFIG_CGROUPS

kernel/cgroup/cgroup.c

+26 −0
Original line number Diff line number Diff line
@@ -577,6 +577,7 @@ struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp, 
	rcu_read_unlock();

	return css;

}

EXPORT_SYMBOL_GPL(cgroup_get_e_css);



static void cgroup_get_live(struct cgroup *cgrp)

{
@@ -5776,6 +5777,31 @@ void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen) 
	kernfs_put(kn);

}



/*

 * cgroup_get_from_id : get the cgroup associated with cgroup id

 * @id: cgroup id

 * On success return the cgrp, on failure return NULL

 */

struct cgroup *cgroup_get_from_id(u64 id)

{

	struct kernfs_node *kn;

	struct cgroup *cgrp = NULL;



	mutex_lock(&cgroup_mutex);

	kn = kernfs_find_and_get_node_by_id(cgrp_dfl_root.kf_root, id);

	if (!kn)

		goto out_unlock;



	cgrp = kn->priv;

	if (cgroup_is_dead(cgrp) || !cgroup_tryget(cgrp))

		cgrp = NULL;

	kernfs_put(kn);

out_unlock:

	mutex_unlock(&cgroup_mutex);

	return cgrp;

}

EXPORT_SYMBOL_GPL(cgroup_get_from_id);



/*

 * proc_cgroup_show()

 *  - Print task's cgroup paths into seq_file, one line for each hierarchy