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cgroup: Implement cgroup_file_show()

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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 <zhouchengming@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-10-tj@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tejun Heo 2022-08-27 19:04:40 -10:00 • committed by Greg Kroah-Hartman
parent 783bd07d09
commit e2691f6b44
2 changed files with 21 additions and 0 deletions
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20
kernel/cgroup/cgroup.c
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@ -4339,6 +4339,26 @@ void cgroup_file_notify(struct cgroup_file *cfile)
spin_unlock_irqrestore(&cgroup_file_kn_lock, flags);
}
/**
* 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)