cgroup: deal with dummp_top in cgroup_name() and cgroup_path()
My kernel fails to boot, because blkcg calls cgroup_path() while
cgroupfs is not mounted.
Fix both cgroup_name() and cgroup_path().
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index ef0b3af..8c283a9 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -487,13 +487,21 @@
static inline int cgroup_name(struct cgroup *cgrp, char *buf, size_t buflen)
{
- return kernfs_name(cgrp->kn, buf, buflen);
+ /* dummy_top doesn't have a kn associated */
+ if (cgrp->kn)
+ return kernfs_name(cgrp->kn, buf, buflen);
+ else
+ return strlcpy(buf, "/", buflen);
}
static inline char * __must_check cgroup_path(struct cgroup *cgrp, char *buf,
size_t buflen)
{
- return kernfs_path(cgrp->kn, buf, buflen);
+ /* dummy_top doesn't have a kn associated */
+ if (cgrp->kn)
+ return kernfs_path(cgrp->kn, buf, buflen);
+ strlcpy(buf, "/", buflen);
+ return (buflen <= 2) ? NULL : buf;
}
static inline void pr_cont_cgroup_name(struct cgroup *cgrp)