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authorTejun Heo <tj@kernel.org>2013-04-14 20:50:08 -0700
committerTejun Heo <tj@kernel.org>2013-05-14 11:42:07 -0700
commit857a2beb09ab83e9a8185821ae16db7dfbe8b837 (patch)
tree2ea1456855d7046dd5503cd7a0a6c78e804aa299 /kernel/cgroup.c
parent1a574231669f8c3065c83974e9557fcbbd94b8a6 (diff)
cgroup: implement task_cgroup_path_from_hierarchy()
kdbus folks want a sane way to determine the cgroup path that a given task belongs to on a given hierarchy, which is a reasonble thing to expect from cgroup core. Implement task_cgroup_path_from_hierarchy(). v2: Dropped unnecessary NULL check on the return value of task_cgroup_from_root() as suggested by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Greg Kroah-Hartman <greg@kroah.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Kay Sievers <kay@vrfy.org> Cc: Lennart Poettering <lennart@poettering.net> Cc: Daniel Mack <daniel@zonque.org>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c32
1 files changed, 32 insertions, 0 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index dcb417c6c24..6b2b1d945df 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1827,6 +1827,38 @@ out:
}
EXPORT_SYMBOL_GPL(cgroup_path);
+/**
+ * task_cgroup_path_from_hierarchy - cgroup path of a task on a hierarchy
+ * @task: target task
+ * @hierarchy_id: the hierarchy to look up @task's cgroup from
+ * @buf: the buffer to write the path into
+ * @buflen: the length of the buffer
+ *
+ * Determine @task's cgroup on the hierarchy specified by @hierarchy_id and
+ * copy its path into @buf. This function grabs cgroup_mutex and shouldn't
+ * be used inside locks used by cgroup controller callbacks.
+ */
+int task_cgroup_path_from_hierarchy(struct task_struct *task, int hierarchy_id,
+ char *buf, size_t buflen)
+{
+ struct cgroupfs_root *root;
+ struct cgroup *cgrp = NULL;
+ int ret = -ENOENT;
+
+ mutex_lock(&cgroup_mutex);
+
+ root = idr_find(&cgroup_hierarchy_idr, hierarchy_id);
+ if (root) {
+ cgrp = task_cgroup_from_root(task, root);
+ ret = cgroup_path(cgrp, buf, buflen);
+ }
+
+ mutex_unlock(&cgroup_mutex);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(task_cgroup_path_from_hierarchy);
+
/*
* Control Group taskset
*/