This is a note to let you know that I've just added the patch titled
scsi: cgroup: Add cgroup_get_from_id()
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
scsi-cgroup-add-cgroup_get_from_id.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 382b7cee9ee1b4dce0d393c1d94a2bfdc0aff047
Author: Muneendra Kumar <muneendra.kumar@xxxxxxxxxxxx>
Date: Tue Jun 8 10:05:44 2021 +0530
scsi: cgroup: Add cgroup_get_from_id()
[ Upstream commit 6b658c4863c15936872a93c9ee879043bf6393c9 ]
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@xxxxxxxxxxxx
Reviewed-by: Himanshu Madhani <himanshu.madhani@xxxxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Muneendra Kumar <muneendra.kumar@xxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Stable-dep-of: 74e4b956eb1c ("cgroup: Honor caller's cgroup NS when resolving path")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 618838c48313..23375d4ccfa0 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 inline 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 0eb05cbafa71..c420b048466b 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)
{
@@ -5921,6 +5922,31 @@ 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
