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blk-mq: avoid to touch q->elevator without any protection

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q->elevator is referred in blk_mq_has_sqsched() without any protection,
no .q_usage_counter is held, no queue srcu and rcu read lock is held,
so potential use-after-free may be triggered.

Fix the issue by adding one queue flag for checking if the elevator
uses single queue style dispatch. Meantime the elevator feature flag
of ELEVATOR_F_MQ_AWARE isn't needed any more.

Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220616014401.817001-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2022-06-16 09:44:00 +08:00 committed by Jens Axboe
parent 5fd7a84a09
commit 4d337cebcb
6 changed files with 13 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
block/bfq-iosched.c
View File

@ -7188,6 +7188,9 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
bfq_init_root_group(bfqd->root_group, bfqd);
bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group);
/* We dispatch from request queue wide instead of hw queue */
blk_queue_flag_set(QUEUE_FLAG_SQ_SCHED, q);
wbt_disable_default(q);
return 0;

1
block/blk-mq-sched.c
View File

@ -564,6 +564,7 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
int ret;
if (!e) {
blk_queue_flag_clear(QUEUE_FLAG_SQ_SCHED, q);
q->elevator = NULL;
q->nr_requests = q->tag_set->queue_depth;
return 0;

18
block/blk-mq.c
View File

@ -2142,20 +2142,6 @@ void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
}
EXPORT_SYMBOL(blk_mq_run_hw_queue);
/*
* Is the request queue handled by an IO scheduler that does not respect
* hardware queues when dispatching?
*/
static bool blk_mq_has_sqsched(struct request_queue *q)
{
struct elevator_queue *e = q->elevator;
if (e && e->type->ops.dispatch_request &&
!(e->type->elevator_features & ELEVATOR_F_MQ_AWARE))
return true;
return false;
}
/*
* Return prefered queue to dispatch from (if any) for non-mq aware IO
* scheduler.
@ -2188,7 +2174,7 @@ void blk_mq_run_hw_queues(struct request_queue *q, bool async)
unsigned long i;
sq_hctx = NULL;
if (blk_mq_has_sqsched(q))
if (blk_queue_sq_sched(q))
sq_hctx = blk_mq_get_sq_hctx(q);
queue_for_each_hw_ctx(q, hctx, i) {
if (blk_mq_hctx_stopped(hctx))
@ -2216,7 +2202,7 @@ void blk_mq_delay_run_hw_queues(struct request_queue *q, unsigned long msecs)
unsigned long i;
sq_hctx = NULL;
if (blk_mq_has_sqsched(q))
if (blk_queue_sq_sched(q))
sq_hctx = blk_mq_get_sq_hctx(q);
queue_for_each_hw_ctx(q, hctx, i) {
if (blk_mq_hctx_stopped(hctx))

3
block/kyber-iosched.c
View File

@ -421,6 +421,8 @@ static int kyber_init_sched(struct request_queue *q, struct elevator_type *e)
blk_stat_enable_accounting(q);
blk_queue_flag_clear(QUEUE_FLAG_SQ_SCHED, q);
eq->elevator_data = kqd;
q->elevator = eq;
@ -1033,7 +1035,6 @@ static struct elevator_type kyber_sched = {
#endif
.elevator_attrs = kyber_sched_attrs,
.elevator_name = "kyber",
.elevator_features = ELEVATOR_F_MQ_AWARE,
.elevator_owner = THIS_MODULE,
};

3
block/mq-deadline.c
View File

@ -642,6 +642,9 @@ static int dd_init_sched(struct request_queue *q, struct elevator_type *e)
spin_lock_init(&dd->lock);
spin_lock_init(&dd->zone_lock);
/* We dispatch from request queue wide instead of hw queue */
blk_queue_flag_set(QUEUE_FLAG_SQ_SCHED, q);
q->elevator = eq;
return 0;

4
include/linux/blkdev.h
View File

@ -575,6 +575,7 @@ struct request_queue {
#define QUEUE_FLAG_RQ_ALLOC_TIME 27 /* record rq->alloc_time_ns */
#define QUEUE_FLAG_HCTX_ACTIVE 28 /* at least one blk-mq hctx is active */
#define QUEUE_FLAG_NOWAIT 29 /* device supports NOWAIT */
#define QUEUE_FLAG_SQ_SCHED 30 /* single queue style io dispatch */
#define QUEUE_FLAG_MQ_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
(1 << QUEUE_FLAG_SAME_COMP) | \
@ -616,6 +617,7 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q);
#define blk_queue_pm_only(q) atomic_read(&(q)->pm_only)
#define blk_queue_registered(q) test_bit(QUEUE_FLAG_REGISTERED, &(q)->queue_flags)
#define blk_queue_nowait(q) test_bit(QUEUE_FLAG_NOWAIT, &(q)->queue_flags)
#define blk_queue_sq_sched(q) test_bit(QUEUE_FLAG_SQ_SCHED, &(q)->queue_flags)
extern void blk_set_pm_only(struct request_queue *q);
extern void blk_clear_pm_only(struct request_queue *q);
@ -1006,8 +1008,6 @@ void disk_set_independent_access_ranges(struct gendisk *disk,
*/
/* Supports zoned block devices sequential write constraint */
#define ELEVATOR_F_ZBD_SEQ_WRITE (1U << 0)
/* Supports scheduling on multiple hardware queues */
#define ELEVATOR_F_MQ_AWARE (1U << 1)
extern void blk_queue_required_elevator_features(struct request_queue *q,
unsigned int features);