Commit e09aae7e authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

blk-mq: release mq's kobjects in blk_release_queue() 



The kobject memory inside blk-mq hctx/ctx shouldn't have been freed
before the kobject is released because driver core can access it freely
before its release.

We can't do that in all ctx/hctx/mq_kobj's release handler because
it can be run before blk_cleanup_queue().

Given mq_kobj shouldn't have been introduced, this patch simply moves
mq's release into blk_release_queue().

Reported-by: default avatarSasha Levin <sasha.levin@oracle.com>
Signed-off-by: default avatarMing Lei <ming.lei@canonical.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 74170118

block/blk-mq.c

+22 −7
Original line number Diff line number Diff line
@@ -1641,10 +1641,8 @@ static void blk_mq_free_hw_queues(struct request_queue *q, 
	struct blk_mq_hw_ctx *hctx;

	unsigned int i;



	queue_for_each_hw_ctx(q, hctx, i) {

	queue_for_each_hw_ctx(q, hctx, i)

		free_cpumask_var(hctx->cpumask);

		kfree(hctx);

	}

}



static int blk_mq_init_hctx(struct request_queue *q,
@@ -1869,6 +1867,27 @@ static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set, 
	mutex_unlock(&set->tag_list_lock);

}



/*

 * It is the actual release handler for mq, but we do it from

 * request queue's release handler for avoiding use-after-free

 * and headache because q->mq_kobj shouldn't have been introduced,

 * but we can't group ctx/kctx kobj without it.

 */

void blk_mq_release(struct request_queue *q)

{

	struct blk_mq_hw_ctx *hctx;

	unsigned int i;



	/* hctx kobj stays in hctx */

	queue_for_each_hw_ctx(q, hctx, i)

		kfree(hctx);



	kfree(q->queue_hw_ctx);



	/* ctx kobj stays in queue_ctx */

	free_percpu(q->queue_ctx);

}



struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)

{

	struct blk_mq_hw_ctx **hctxs;
@@ -2002,12 +2021,8 @@ void blk_mq_free_queue(struct request_queue *q) 


	percpu_ref_exit(&q->mq_usage_counter);



	free_percpu(q->queue_ctx);

	kfree(q->queue_hw_ctx);

	kfree(q->mq_map);



	q->queue_ctx = NULL;

	q->queue_hw_ctx = NULL;

	q->mq_map = NULL;



	mutex_lock(&all_q_mutex);

block/blk-mq.h

+2 −0
Original line number Diff line number Diff line
@@ -62,6 +62,8 @@ extern void blk_mq_sysfs_unregister(struct request_queue *q); 


extern void blk_mq_rq_timed_out(struct request *req, bool reserved);



void blk_mq_release(struct request_queue *q);



/*

 * Basic implementation of sparser bitmap, allowing the user to spread

 * the bits over more cachelines.

block/blk-sysfs.c

+2 −0
Original line number Diff line number Diff line
@@ -517,6 +517,8 @@ static void blk_release_queue(struct kobject *kobj) 


	if (!q->mq_ops)

		blk_free_flush_queue(q->fq);

	else

		blk_mq_release(q);



	blk_trace_shutdown(q);

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