From 6b658c4863c15936872a93c9ee879043bf6393c9 Mon Sep 17 00:00:00 2001 From: Muneendra Kumar Date: Tue, 8 Jun 2021 10:05:44 +0530 Subject: 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: Himanshu Madhani Reviewed-by: Hannes Reinecke Acked-by: Tejun Heo Signed-off-by: Muneendra Kumar Signed-off-by: Martin K. Petersen --- kernel/cgroup/cgroup.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'kernel/cgroup/cgroup.c') diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index e049edd66776..692779d3cdfa 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -577,6 +577,7 @@ out_unlock: 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 -- cgit v1.2.3