[PATCH RFC 2/9] block, bfq: apply news apis where root group is not expected

From: Yu Kuai
Date: Sat Nov 27 2021 - 05:01:29 EST


'entity->sched_data' is set to parent group's sched_data, thus it's NULL
for root group. And for_each_entity() is used widely to access
'entity->sched_data', thus aplly news apis if root group is not
expected. The case that root group is expected will be handled in next
patch.

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
block/bfq-iosched.c | 2 +-
block/bfq-iosched.h | 22 ++++++++--------------
block/bfq-wf2q.c | 10 +++++-----
3 files changed, 14 insertions(+), 20 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 1ce1a99a7160..3262d062e21f 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -4273,7 +4273,7 @@ void bfq_bfqq_expire(struct bfq_data *bfqd,
* service with the same budget.
*/
entity = entity->parent;
- for_each_entity(entity)
+ for_each_entity_not_root(entity)
entity->service = 0;
}

diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index f5afc80ff11c..ef875b8046e5 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -1021,25 +1021,22 @@ extern struct blkcg_policy blkcg_policy_bfq;
/* - interface of the internal hierarchical B-WF2Q+ scheduler - */

#ifdef CONFIG_BFQ_GROUP_IOSCHED
-/* both next loops stop at one of the child entities of the root group */
+/* stop at one of the child entities of the root group */
#define for_each_entity(entity) \
for (; entity ; entity = entity->parent)

-/*
- * For each iteration, compute parent in advance, so as to be safe if
- * entity is deallocated during the iteration. Such a deallocation may
- * happen as a consequence of a bfq_put_queue that frees the bfq_queue
- * containing entity.
- */
-#define for_each_entity_safe(entity, parent) \
- for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
-
#define is_root_entity(entity) \
(entity->sched_data == NULL)

#define for_each_entity_not_root(entity) \
for (; entity && !is_root_entity(entity); entity = entity->parent)

+/*
+ * For each iteration, compute parent in advance, so as to be safe if
+ * entity is deallocated during the iteration. Such a deallocation may
+ * happen as a consequence of a bfq_put_queue that frees the bfq_queue
+ * containing entity.
+ */
#define for_each_entity_not_root_safe(entity, parent) \
for (; entity && !is_root_entity(entity) && \
({ parent = entity->parent; 1; }); entity = parent)
@@ -1047,16 +1044,13 @@ extern struct blkcg_policy blkcg_policy_bfq;
#define is_root_entity(entity) (false)

/*
- * Next four macros are fake loops when cgroups support is not
+ * Next three macros are fake loops when cgroups support is not
* enabled. I fact, in such a case, there is only one level to go up
* (to reach the root group).
*/
#define for_each_entity(entity) \
for (; entity ; entity = NULL)

-#define for_each_entity_safe(entity, parent) \
- for (parent = NULL; entity ; entity = parent)
-
#define for_each_entity_not_root(entity) \
for (; entity ; entity = NULL)

diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
index b74cc0da118e..67e32481e455 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c
@@ -830,7 +830,7 @@ void bfq_bfqq_served(struct bfq_queue *bfqq, int served)
bfqq->service_from_wr += served;

bfqq->service_from_backlogged += served;
- for_each_entity(entity) {
+ for_each_entity_not_root(entity) {
st = bfq_entity_service_tree(entity);

entity->service += served;
@@ -1216,7 +1216,7 @@ static void bfq_deactivate_entity(struct bfq_entity *entity,
struct bfq_sched_data *sd;
struct bfq_entity *parent = NULL;

- for_each_entity_safe(entity, parent) {
+ for_each_entity_not_root_safe(entity, parent) {
sd = entity->sched_data;

if (!__bfq_deactivate_entity(entity, ins_into_idle_tree)) {
@@ -1285,7 +1285,7 @@ static void bfq_deactivate_entity(struct bfq_entity *entity,
* is not the case.
*/
entity = parent;
- for_each_entity(entity) {
+ for_each_entity_not_root(entity) {
/*
* Invoke __bfq_requeue_entity on entity, even if
* already active, to requeue/reposition it in the
@@ -1585,7 +1585,7 @@ struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
* We can finally update all next-to-serve entities along the
* path from the leaf entity just set in service to the root.
*/
- for_each_entity(entity) {
+ for_each_entity_not_root(entity) {
struct bfq_sched_data *sd = entity->sched_data;

if (!bfq_update_next_in_service(sd, NULL, false))
@@ -1612,7 +1612,7 @@ bool __bfq_bfqd_reset_in_service(struct bfq_data *bfqd)
* execute the final step: reset in_service_entity along the
* path from entity to the root.
*/
- for_each_entity(entity)
+ for_each_entity_not_root(entity)
entity->sched_data->in_service_entity = NULL;

/*
--
2.31.1