linux-kernel - [PATCH] elevator: fix double release for elevator module

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Message-id: <005701d07da7$364d9950$a2e8cbf0$@samsung.com>
Date:	Thu, 23 Apr 2015 17:23:18 +0800
From:	Chao Yu <chao2.yu@...sung.com>
To:	axboe@...nel.dk
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] elevator: fix double release for elevator module

Our issue is descripted in below call path:
->elevator_init
 ->elevator_init_fn
  ->{cfq,deadline,noop}_init_queue
   ->elevator_alloc
    ->kzalloc_node
   fail to call kzalloc_node and then put module in elevator_alloc;
fail to call elevator_init_fn and then put module again in elevator_init.

Remove elevator_put invoking in error path of elevator_alloc to avoid
double release issue.

Signed-off-by: Chao Yu <chao2.yu@...sung.com>
---
 block/elevator.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/block/elevator.c b/block/elevator.c
index d146a5e..8985038 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -157,7 +157,7 @@ struct elevator_queue *elevator_alloc(struct request_queue *q,
 
 	eq = kzalloc_node(sizeof(*eq), GFP_KERNEL, q->node);
 	if (unlikely(!eq))
-		goto err;
+		return NULL;
 
 	eq->type = e;
 	kobject_init(&eq->kobj, &elv_ktype);
@@ -165,9 +165,6 @@ struct elevator_queue *elevator_alloc(struct request_queue *q,
 	hash_init(eq->hash);
 
 	return eq;
-err:
-	elevator_put(e);
-	return NULL;
 }
 EXPORT_SYMBOL(elevator_alloc);
 
-- 
2.3.3


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