Added a new function cgroup_get_from_id to retrieve the cgroup
associated with cgroup id.
Exported the same as this can be used by blk-cgorup.c
Added function declaration of cgroup_get_from_id in cgorup.h
This patch also exported the function cgroup_get_e_css
as this is getting used in blk-cgroup.h
Signed-off-by: Muneendra <muneendra.kumar@xxxxxxxxxxxx>
---
v6:
No change
v5:
renamed the function cgroup_get_from_kernfs_id to
cgroup_get_from_id
v4:
No change
v3:
Exported the cgroup_get_e_css
v2:
New patch
---
include/linux/cgroup.h | 6 ++++++
kernel/cgroup/cgroup.c | 26 ++++++++++++++++++++++++++
2 files changed, 32 insertions(+)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 618838c48313..da31b14db198 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -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 struct cgroup *cgroup_get_from_id(u64 id)
+{
+ return NULL;
+}
#endif /* !CONFIG_CGROUPS */
#ifdef CONFIG_CGROUPS
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index e41c21819ba0..34ebfbeba098 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -580,6 +580,7 @@ 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)
{
@@ -5805,6 +5806,31 @@ 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 it returns the cgrp on failure it returns 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
--
2.26.2
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