cgroup: Expose some cgroup helpers

Expose the following through cgroup.h:

- cgroup_on_dfl()
- cgroup_is_dead()
- cgroup_for_each_live_child()
- cgroup_for_each_live_descendant_pre()
- cgroup_for_each_live_descendant_post()

Until now, these didn't need to be exposed because controllers only cared
about the css hierarchy. The planned sched_ext hierarchical scheduler
support will be based on the default cgroup hierarchy, which is in line
with the existing BPF cgroup support, and thus needs these exposed.

Signed-off-by: Tejun Heo <tj@kernel.org>

2 files changed, 0 insertions, 61 deletions

diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index 3bfe37693d68..58797123b752 100644
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -184,11 +184,6 @@ extern bool cgrp_dfl_visible;
 	for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT &&		\
 	     (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
 
-static inline bool cgroup_is_dead(const struct cgroup *cgrp)
-{
-	return !(cgrp->self.flags & CSS_ONLINE);
-}
-
 static inline bool notify_on_release(const struct cgroup *cgrp)
 {
 	return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
@@ -222,7 +217,6 @@ static inline void get_css_set(struct css_set *cset)
 }
 
 bool cgroup_ssid_enabled(int ssid);
-bool cgroup_on_dfl(const struct cgroup *cgrp);
 
 struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);
 struct cgroup *task_cgroup_from_root(struct task_struct *task,
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index be1d71dda317..cdc63be63f2c 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -69,14 +69,6 @@
 #define CGROUP_FILE_NOTIFY_MIN_INTV	DIV_ROUND_UP(HZ, 100)
 
 /*
- * To avoid confusing the compiler (and generating warnings) with code
- * that attempts to access what would be a 0-element array (i.e. sized
- * to a potentially empty array when CGROUP_SUBSYS_COUNT == 0), this
- * constant expression can be added.
- */
-#define CGROUP_HAS_SUBSYS_CONFIG	(CGROUP_SUBSYS_COUNT > 0)
-
-/*
  * cgroup_mutex is the master lock.  Any modification to cgroup or its
  * hierarchy must be performed while holding it.
  *
@@ -510,27 +502,6 @@ static u32 cgroup_ss_mask(struct cgroup *cgrp)
 }
 
 /**
- * cgroup_css - obtain a cgroup's css for the specified subsystem
- * @cgrp: the cgroup of interest
- * @ss: the subsystem of interest (%NULL returns @cgrp->self)
- *
- * Return @cgrp's css (cgroup_subsys_state) associated with @ss.  This
- * function must be called either under cgroup_mutex or rcu_read_lock() and
- * the caller is responsible for pinning the returned css if it wants to
- * keep accessing it outside the said locks.  This function may return
- * %NULL if @cgrp doesn't have @subsys_id enabled.
- */
-static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp,
-					      struct cgroup_subsys *ss)
-{
-	if (CGROUP_HAS_SUBSYS_CONFIG && ss)
-		return rcu_dereference_check(cgrp->subsys[ss->id],
-					lockdep_is_held(&cgroup_mutex));
-	else
-		return &cgrp->self;
-}
-
-/**
  * cgroup_e_css_by_mask - obtain a cgroup's effective css for the specified ss
  * @cgrp: the cgroup of interest
  * @ss: the subsystem of interest (%NULL returns @cgrp->self)
@@ -741,32 +712,6 @@ EXPORT_SYMBOL_GPL(of_css);
 	}								\
 } while (false)
 
-/* iterate over child cgrps, lock should be held throughout iteration */
-#define cgroup_for_each_live_child(child, cgrp)				\
-	list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \
-		if (({ lockdep_assert_held(&cgroup_mutex);		\
-		       cgroup_is_dead(child); }))			\
-			;						\
-		else
-
-/* walk live descendants in pre order */
-#define cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp)		\
-	css_for_each_descendant_pre((d_css), cgroup_css((cgrp), NULL))	\
-		if (({ lockdep_assert_held(&cgroup_mutex);		\
-		       (dsct) = (d_css)->cgroup;			\
-		       cgroup_is_dead(dsct); }))			\
-			;						\
-		else
-
-/* walk live descendants in postorder */
-#define cgroup_for_each_live_descendant_post(dsct, d_css, cgrp)		\
-	css_for_each_descendant_post((d_css), cgroup_css((cgrp), NULL))	\
-		if (({ lockdep_assert_held(&cgroup_mutex);		\
-		       (dsct) = (d_css)->cgroup;			\
-		       cgroup_is_dead(dsct); }))			\
-			;						\
-		else
-
 /*
  * The default css_set - used by init and its children prior to any
  * hierarchies being mounted. It contains a pointer to the root state