We should move the list operation after validation.

Signed-off-by: Baolin Wang <baolin.w...@linux.alibaba.com>
---
 block/blk-throttle.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 0649bce..f1bcb5c 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -423,12 +423,13 @@ static void throtl_qnode_add_bio(struct bio *bio, struct 
throtl_qnode *qn,
  */
 static struct bio *throtl_peek_queued(struct list_head *queued)
 {
-       struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, 
node);
+       struct throtl_qnode *qn;
        struct bio *bio;
 
        if (list_empty(queued))
                return NULL;
 
+       qn = list_first_entry(queued, struct throtl_qnode, node);
        bio = bio_list_peek(&qn->bios);
        WARN_ON_ONCE(!bio);
        return bio;
@@ -451,12 +452,13 @@ static struct bio *throtl_peek_queued(struct list_head 
*queued)
 static struct bio *throtl_pop_queued(struct list_head *queued,
                                     struct throtl_grp **tg_to_put)
 {
-       struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, 
node);
+       struct throtl_qnode *qn;
        struct bio *bio;
 
        if (list_empty(queued))
                return NULL;
 
+       qn = list_first_entry(queued, struct throtl_qnode, node);
        bio = bio_list_pop(&qn->bios);
        WARN_ON_ONCE(!bio);
 
-- 
1.8.3.1

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