Il giorno 27 nov 2021, alle ore 11:11, Yu Kuai [off-list ref] ha scritto:

Prevent null-ptr-deref after counting root group into
'num_groups_with_pending_reqs'.

Signed-off-by: Yu Kuai <redacted>
---
block/bfq-iosched.c |  2 +-
block/bfq-wf2q.c    | 17 +++++++++++++----
2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 3262d062e21f..47722f931ee3 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c

@@ -864,7 +864,7 @@ void bfq_weights_tree_remove(struct bfq_data *bfqd,

	for_each_entity(entity) {
		struct bfq_sched_data *sd = entity->my_sched_data;

-		if (sd->next_in_service || sd->in_service_entity) {
+		if (sd && (sd->next_in_service || sd->in_service_entity)) {

			/*
			 * entity is still active, because either
			 * next_in_service or in_service_entity is not

diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
index 67e32481e455..6693765ff3a0 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c

@@ -965,6 +965,13 @@ static void __bfq_activate_entity(struct bfq_entity *entity,

	bool backshifted = false;
	unsigned long long min_vstart;

+	if (is_root_entity(entity))
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+		goto update;
+#else
+		return;
+#endif
+
	/* See comments on bfq_fqq_update_budg_for_activation */
	if (non_blocking_wait_rq && bfq_gt(st->vtime, entity->finish)) {
		backshifted = true;

@@ -999,7 +1006,10 @@ static void __bfq_activate_entity(struct bfq_entity *entity,

		entity->on_st_or_in_serv = true;
	}

+	bfq_update_fin_time_enqueue(entity, st, backshifted);
+
#ifdef CONFIG_BFQ_GROUP_IOSCHED
+update:
	if (!bfq_entity_to_bfqq(entity)) { /* bfq_group */
		struct bfq_group *bfqg =
			container_of(entity, struct bfq_group, entity);

@@ -1011,8 +1021,6 @@ static void __bfq_activate_entity(struct bfq_entity *entity,

		}
	}
#endif
-
-	bfq_update_fin_time_enqueue(entity, st, backshifted);
}

/**

@@ -1102,7 +1110,8 @@ static void __bfq_activate_requeue_entity(struct bfq_entity *entity,

{
	struct bfq_service_tree *st = bfq_entity_service_tree(entity);

-	if (sd->in_service_entity == entity || entity->tree == &st->active)
+	if (sd && (sd->in_service_entity == entity ||
+		   entity->tree == &st->active))
		 /*
		  * in service or already queued on the active tree,
		  * requeue or reposition

@@ -1140,7 +1149,7 @@ static void bfq_activate_requeue_entity(struct bfq_entity *entity,

		sd = entity->sched_data;
		__bfq_activate_requeue_entity(entity, sd, non_blocking_wait_rq);

-		if (!bfq_update_next_in_service(sd, entity, expiration) &&
+		if (sd && !bfq_update_next_in_service(sd, entity, expiration) &&
		    !requeue)
			break;
	}
-- 
2.31.1