From e2691f6b44ed2135bfd005ad5fbabac4f433a7a1 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sat, 27 Aug 2022 19:04:40 -1000 Subject: [PATCH] cgroup: Implement cgroup_file_show() Add cgroup_file_show() which allows toggling visibility of a cgroup file using the new kernfs_show(). This will be used to hide psi interface files on cgroups where it's disabled. Cc: Chengming Zhou Cc: Johannes Weiner Tested-by: Chengming Zhou Reviewed-by: Chengming Zhou Signed-off-by: Tejun Heo Link: https://lore.kernel.org/r/20220828050440.734579-10-tj@kernel.org Signed-off-by: Greg Kroah-Hartman --- include/linux/cgroup.h | 1 + kernel/cgroup/cgroup.c | 20 ++++++++++++++++++++ 2 files changed, 21 insertions(+) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index ed53bfe..f61dd135 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -114,6 +114,7 @@ int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); 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); diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index ffaccd6..217469a 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -4340,6 +4340,26 @@ void cgroup_file_notify(struct cgroup_file *cfile) } /** + * cgroup_file_show - show or hide a hidden cgroup file + * @cfile: target cgroup_file obtained by setting cftype->file_offset + * @show: whether to show or hide + */ +void cgroup_file_show(struct cgroup_file *cfile, bool show) +{ + struct kernfs_node *kn; + + spin_lock_irq(&cgroup_file_kn_lock); + kn = cfile->kn; + kernfs_get(kn); + spin_unlock_irq(&cgroup_file_kn_lock); + + if (kn) + kernfs_show(kn, show); + + kernfs_put(kn); +} + +/** * css_next_child - find the next child of a given css * @pos: the current position (%NULL to initiate traversal) * @parent: css whose children to walk -- 2.7.4