linux-kernel - [PATCH] blk-mq: clear q->mq

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Date:	Wed, 25 May 2016 23:23:27 -0700
From:	Ming Lin <mlin@...nel.org>
To:	linux-kernel@...r.kernel.org, linux-block@...r.kernel.org
Cc:	Jens Axboe <axboe@...com>, Christoph Hellwig <hch@....de>
Subject: [PATCH] blk-mq: clear q->mq_ops if init fail

From: Ming Lin <ming.l@...sung.com>

blk_mq_init_queue() calls blk_mq_init_allocated_queue(), but q->mq_ops
was not cleared when blk_mq_init_allocated_queue() fails.
Then blk_cleanup_queue() calls blk_mq_free_queue() which will crash because:
- q->all_q_node is not added to all_q_list yet
- q->tag_set is NULL
- hctx was not setup yet or already freed

Fixed it by clearing q->mq_ops on error path.

Signed-off-by: Ming Lin <ming.l@...sung.com>
---
 block/blk-mq.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 67bf8ed..86f08b1 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2054,7 +2054,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 
 	q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
 	if (!q->queue_ctx)
-		return ERR_PTR(-ENOMEM);
+		goto err_exit;
 
 	q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
 						GFP_KERNEL, set->numa_node);
@@ -2118,6 +2118,8 @@ err_map:
 	kfree(q->queue_hw_ctx);
 err_percpu:
 	free_percpu(q->queue_ctx);
+err_exit:
+	q->mq_ops = NULL;
 	return ERR_PTR(-ENOMEM);
 }
 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
-- 
1.9.1