[PATCH 5/7] blktrace: report EBUSY correctly

[Li Zefan <lizf@cn.fujitsu.com>]

blk_trace_remove_queue() returns EINVAL if q->blk_trace == NULL,
but blk_trace_setup_queue() doesn't return EBUSY if q->blk_trace != NULL.

 # echo 0 > sdaX/trace/enable
 # echo 0 > sdaX/trace/enable
 bash: echo: write error: Invalid argument
 # echo 1 > sdaX/trace/enable
 # echo 1 > sdaX/trace/enable
 (should return EBUSY)

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
 kernel/trace/blktrace.c |    9 +++------
 1 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 11e7c8d..14986af 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -1260,12 +1260,10 @@ static int blk_trace_remove_queue(struct request_queue *q)
 static int blk_trace_setup_queue(struct request_queue *q, dev_t dev)
 {
 	struct blk_trace *old_bt, *bt = NULL;
-	int ret;
 
-	ret = -ENOMEM;
 	bt = kzalloc(sizeof(*bt), GFP_KERNEL);
 	if (!bt)
-		goto err;
+		return -ENOMEM;
 
 	bt->dev = dev;
 	bt->act_mask = (u16)-1;
@@ -1276,11 +1274,10 @@ static int blk_trace_setup_queue(struct request_queue *q, dev_t dev)
 	if (old_bt != NULL) {
 		(void)xchg(&q->blk_trace, old_bt);
 		kfree(bt);
-		ret = -EBUSY;
+		return -EBUSY;
 	}
+
 	return 0;
-err:
-	return ret;
 }
 
 /*
-- 
1.5.4.rc3