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scsi: cgroup: Add cgroup_get_from_id()

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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: Himanshu Madhani <himanshu.madhani@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Muneendra Kumar <muneendra.kumar@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Muneendra Kumar 2021-06-08 10:05:44 +05:30 committed by Martin K. Petersen
parent 49d3e59961
commit 6b658c4863
2 changed files with 32 additions and 0 deletions
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6
include/linux/cgroup.h
View file

@ -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

26
kernel/cgroup/cgroup.c
View file

@ -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