path: root/block
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authorTejun Heo <>2014-02-12 09:29:50 -0500
committerTejun Heo <>2014-02-12 09:29:50 -0500
commite61734c55c24cdf11b07e52a74aec4dc4a7f4bd0 (patch)
treebab256faae539cd38840bfc886317f80385acae4 /block
parent6f30558f37bfbd428e3854c2c34b5c32117c8f7e (diff)
cgroup: remove cgroup->name
cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <> Acked-by: Peter Zijlstra <> Acked-by: Michal Hocko <> Acked-by: Li Zefan <> Cc: Fengguang Wu <> Cc: Ingo Molnar <> Cc: Johannes Weiner <> Cc: Balbir Singh <> Cc: KAMEZAWA Hiroyuki <>
Diffstat (limited to 'block')
1 files changed, 8 insertions, 4 deletions
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 453b528..15a8d64 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -241,12 +241,16 @@ static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
- int ret;
+ char *p;
- ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
- if (ret)
+ p = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
+ if (!p) {
strncpy(buf, "<unavailable>", buflen);
- return ret;
+ }
+ memmove(buf, p, buf + buflen - p);
+ return 0;