From: Seung-Woo Kim <sw0312.kim@samsung.com>
Date: Tue, 27 Feb 2024 09:18:07 +0000 (+0900)
Subject: kdbus: Revert "cgroup: remove unused task_cgroup_path()"
X-Git-Tag: accepted/tizen/unified/20240422.153132~24
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0cb791f04e9446644326ad09f22b9701ea11796d;hp=1fd25f5f88e058ef2a184e8bae3b82b749b6c67a;p=platform%2Fkernel%2Flinux-rpi.git

kdbus: Revert "cgroup: remove unused task_cgroup_path()"

This reverts commit d16b3af46679a1eb21652c37711a60d3d4e6b8c0.

kdbus of linux-tizen-modules-source has still usage of
task_cgroup_path(). To support linux-tizen-modules-source,
as workaround, revert back.

Change-Id: I0c943932d07ff0aa602f4a238bfa5839d74735d4
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
---

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index b307013..567c547 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -118,6 +118,7 @@ int cgroup_rm_cftypes(struct cftype *cfts);
 void cgroup_file_notify(struct cgroup_file *cfile);
 void cgroup_file_show(struct cgroup_file *cfile, bool show);
 
+int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
 int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry);
 int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
 		     struct pid *pid, struct task_struct *tsk);
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 5165f5c..49e602a 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -2355,6 +2355,45 @@ int cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen,
 EXPORT_SYMBOL_GPL(cgroup_path_ns);
 
 /**
+ * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
+ * @task: target task
+ * @buf: the buffer to write the path into
+ * @buflen: the length of the buffer
+ *
+ * Determine @task's cgroup on the first (the one with the lowest non-zero
+ * hierarchy_id) cgroup hierarchy and copy its path into @buf.  This
+ * function grabs cgroup_mutex and shouldn't be used inside locks used by
+ * cgroup controller callbacks.
+ *
+ * Return value is the same as kernfs_path().
+ */
+int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
+{
+	struct cgroup_root *root;
+	struct cgroup *cgrp;
+	int hierarchy_id = 1;
+	int ret;
+
+	cgroup_lock();
+	spin_lock_irq(&css_set_lock);
+
+	root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id);
+
+	if (root) {
+		cgrp = task_cgroup_from_root(task, root);
+		ret = cgroup_path_ns_locked(cgrp, buf, buflen, &init_cgroup_ns);
+	} else {
+		/* if no hierarchy exists, everyone is in "/" */
+		ret = strscpy(buf, "/", buflen);
+	}
+
+	spin_unlock_irq(&css_set_lock);
+	cgroup_unlock();
+	return ret;
+}
+EXPORT_SYMBOL_GPL(task_cgroup_path);
+
+/**
  * cgroup_attach_lock - Lock for ->attach()
  * @lock_threadgroup: whether to down_write cgroup_threadgroup_rwsem
  *