by tip-bot2 for Eric Biggers

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Subject: [tip: sched/psi] cgroup: Implement cgroup_file_show()

The following commit has been merged into the sched/psi branch of tip:

Commit-ID: e2691f6b44ed2135bfd005ad5fbabac4f433a7a1
Gitweb: https://git.kernel.org/tip/e2691f6b44ed2135bfd005ad5fbabac4f433a7a1
Author: Tejun Heo <[email protected]>
AuthorDate: Sat, 27 Aug 2022 19:04:40 -10:00
Committer: Greg Kroah-Hartman <[email protected]>
CommitterDate: Thu, 01 Sep 2022 18:08:44 +02:00

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 <[email protected]>
Cc: Johannes Weiner <[email protected]>
Tested-by: Chengming Zhou <[email protected]>
Reviewed-by: Chengming Zhou <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
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..f61dd13 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

2022-09-09 14:56:37

by tip-bot2 for Eric Biggers

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Subject: [tip: sched/psi] kernfs: Factor out kernfs_activate_one()

The following commit has been merged into the sched/psi branch of tip:

Commit-ID: f8eb145eb946d543e8c8df3d2db39fcd5c80dacb
Gitweb: https://git.kernel.org/tip/f8eb145eb946d543e8c8df3d2db39fcd5c80dacb
Author: Tejun Heo <[email protected]>
AuthorDate: Sat, 27 Aug 2022 19:04:38 -10:00
Committer: Greg Kroah-Hartman <[email protected]>
CommitterDate: Thu, 01 Sep 2022 18:08:44 +02:00

kernfs: Factor out kernfs_activate_one()

Factor out kernfs_activate_one() from kernfs_activate() and reorder
operations so that KERNFS_ACTIVATED now simply indicates whether activation
was attempted on the node ignoring whether activation took place. As the
flag doesn't have a reader, the refactoring and reordering shouldn't cause
any behavior difference.

Tested-by: Chengming Zhou <[email protected]>
Reviewed-by: Chengming Zhou <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
fs/kernfs/dir.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index f8cbd05..c932395 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -1305,6 +1305,21 @@ static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos,
return pos->parent;
}

+static void kernfs_activate_one(struct kernfs_node *kn)
+{
+ lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem);
+
+ kn->flags |= KERNFS_ACTIVATED;
+
+ if (kernfs_active(kn) || (kn->flags & KERNFS_REMOVING))
+ return;
+
+ WARN_ON_ONCE(kn->parent && RB_EMPTY_NODE(&kn->rb));
+ WARN_ON_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS);
+
+ atomic_sub(KN_DEACTIVATED_BIAS, &kn->active);
+}
+
/**
* kernfs_activate - activate a node which started deactivated
* @kn: kernfs_node whose subtree is to be activated
@@ -1326,16 +1341,8 @@ void kernfs_activate(struct kernfs_node *kn)
down_write(&root->kernfs_rwsem);

pos = NULL;
- while ((pos = kernfs_next_descendant_post(pos, kn))) {
- if (kernfs_active(pos) || (pos->flags & KERNFS_REMOVING))
- continue;
-
- WARN_ON_ONCE(pos->parent && RB_EMPTY_NODE(&pos->rb));
- WARN_ON_ONCE(atomic_read(&pos->active) != KN_DEACTIVATED_BIAS);
-
- atomic_sub(KN_DEACTIVATED_BIAS, &pos->active);
- pos->flags |= KERNFS_ACTIVATED;
- }
+ while ((pos = kernfs_next_descendant_post(pos, kn)))
+ kernfs_activate_one(pos);

up_write(&root->kernfs_rwsem);
}