Reduce rbtree boiler plate by using the new helpers.
Make rb_add_cached() / rb_erase_cached() return a pointer to the
leftmost node to aid in updating additional state.
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
include/linux/rbtree.h | 18 ++++++++---
kernel/sched/deadline.c | 77 +++++++++++++++++-------------------------------
2 files changed, 42 insertions(+), 53 deletions(-)
--- a/include/linux/rbtree.h
+++ b/include/linux/rbtree.h
@@ -141,12 +141,18 @@ static inline void rb_insert_color_cache
rb_insert_color(node, &root->rb_root);
}
-static inline void rb_erase_cached(struct rb_node *node,
- struct rb_root_cached *root)
+
+static inline struct rb_node *
+rb_erase_cached(struct rb_node *node, struct rb_root_cached *root)
{
+ struct rb_node *leftmost = NULL;
+
if (root->rb_leftmost == node)
- root->rb_leftmost = rb_next(node);
+ leftmost = root->rb_leftmost = rb_next(node);
+
rb_erase(node, &root->rb_root);
+
+ return leftmost;
}
static inline void rb_replace_node_cached(struct rb_node *victim,
@@ -179,8 +185,10 @@ static inline void rb_replace_node_cache
* @node: node to insert
* @tree: leftmost cached tree to insert @node into
* @less: operator defining the (partial) node order
+ *
+ * Returns @node when it is the new leftmost, or NULL.
*/
-static __always_inline void
+static __always_inline struct rb_node *
rb_add_cached(struct rb_node *node, struct rb_root_cached *tree,
bool (*less)(struct rb_node *, const struct rb_node *))
{
@@ -200,6 +208,8 @@ rb_add_cached(struct rb_node *node, stru
rb_link_node(node, parent, link);
rb_insert_color_cached(node, tree, leftmost);
+
+ return leftmost ? node : NULL;
}
/**
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -517,58 +517,44 @@ static void dec_dl_migration(struct sche
update_dl_migration(dl_rq);
}
+#define __node_2_pdl(node) \
+ rb_entry((node), struct task_struct, pushable_dl_tasks)
+
+static inline bool __pushable_less(struct rb_node *a, const struct rb_node *b)
+{
+ return dl_entity_preempt(&__node_2_pdl(a)->dl, &__node_2_pdl(b)->dl);
+}
+
/*
* The list of pushable -deadline task is not a plist, like in
* sched_rt.c, it is an rb-tree with tasks ordered by deadline.
*/
static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
{
- struct dl_rq *dl_rq = &rq->dl;
- struct rb_node **link = &dl_rq->pushable_dl_tasks_root.rb_root.rb_node;
- struct rb_node *parent = NULL;
- struct task_struct *entry;
- bool leftmost = true;
+ struct rb_node *leftmost;
BUG_ON(!RB_EMPTY_NODE(&p->pushable_dl_tasks));
- while (*link) {
- parent = *link;
- entry = rb_entry(parent, struct task_struct,
- pushable_dl_tasks);
- if (dl_entity_preempt(&p->dl, &entry->dl))
- link = &parent->rb_left;
- else {
- link = &parent->rb_right;
- leftmost = false;
- }
- }
-
+ leftmost = rb_add_cached(&p->pushable_dl_tasks,
+ &rq->dl.pushable_dl_tasks_root,
+ __pushable_less);
if (leftmost)
- dl_rq->earliest_dl.next = p->dl.deadline;
-
- rb_link_node(&p->pushable_dl_tasks, parent, link);
- rb_insert_color_cached(&p->pushable_dl_tasks,
- &dl_rq->pushable_dl_tasks_root, leftmost);
+ rq->dl.earliest_dl.next = p->dl.deadline;
}
static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
{
struct dl_rq *dl_rq = &rq->dl;
+ struct rb_root_cached *root = &dl_rq->pushable_dl_tasks_root;
+ struct rb_node *leftmost;
if (RB_EMPTY_NODE(&p->pushable_dl_tasks))
return;
- if (dl_rq->pushable_dl_tasks_root.rb_leftmost == &p->pushable_dl_tasks)
{
- struct rb_node *next_node;
-
- next_node = rb_next(&p->pushable_dl_tasks);
- if (next_node) {
- dl_rq->earliest_dl.next = rb_entry(next_node,
- struct task_struct,
pushable_dl_tasks)->dl.deadline;
- }
- }
+ leftmost = rb_erase_cached(&p->pushable_dl_tasks, root);
+ if (leftmost)
+ dl_rq->earliest_dl.next = __node_2_pdl(leftmost)->dl.deadline;
- rb_erase_cached(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
RB_CLEAR_NODE(&p->pushable_dl_tasks);
}
@@ -1478,29 +1464,21 @@ void dec_dl_tasks(struct sched_dl_entity
dec_dl_migration(dl_se, dl_rq);
}
+#define __node_2_dle(node) \
+ rb_entry((node), struct sched_dl_entity, rb_node)
+
+static inline bool __dl_less(struct rb_node *a, const struct rb_node *b)
+{
+ return dl_time_before(__node_2_dle(a)->deadline,
__node_2_dle(b)->deadline);
+}
+
static void __enqueue_dl_entity(struct sched_dl_entity *dl_se)
{
struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
- struct rb_node **link = &dl_rq->root.rb_root.rb_node;
- struct rb_node *parent = NULL;
- struct sched_dl_entity *entry;
- int leftmost = 1;
BUG_ON(!RB_EMPTY_NODE(&dl_se->rb_node));
- while (*link) {
- parent = *link;
- entry = rb_entry(parent, struct sched_dl_entity, rb_node);
- if (dl_time_before(dl_se->deadline, entry->deadline))
- link = &parent->rb_left;
- else {
- link = &parent->rb_right;
- leftmost = 0;
- }
- }
-
- rb_link_node(&dl_se->rb_node, parent, link);
- rb_insert_color_cached(&dl_se->rb_node, &dl_rq->root, leftmost);
+ rb_add_cached(&dl_se->rb_node, &dl_rq->root, __dl_less);
inc_dl_tasks(dl_se, dl_rq);
}
@@ -1513,6 +1491,7 @@ static void __dequeue_dl_entity(struct s
return;
rb_erase_cached(&dl_se->rb_node, &dl_rq->root);
+
RB_CLEAR_NODE(&dl_se->rb_node);
dec_dl_tasks(dl_se, dl_rq);
