block: drop unnecessary blk_get/put_queue() in scsi_cmd_ioctl() and blk_get_tg()

blk_get/put_queue() in scsi_cmd_ioctl() and throtl_get_tg() are
completely bogus.  The caller must have a reference to the queue on
entry and taking an extra reference doesn't change anything.

For scsi_cmd_ioctl(), the only effect is that it ends up checking
QUEUE_FLAG_DEAD on entry; however, this is bogus as queue can die
right after blk_get_queue().  Dead queue should be and is handled in
request issue path (it's somewhat broken now but that's a separate
problem and doesn't affect this one much).

throtl_get_tg() incorrectly assumes that q is rcu freed.  Also, it
doesn't check return value of blk_get_queue().  If the queue is
already dead, it ends up doing an extra put.

Drop them.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 1 insertions, 7 deletions

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index f3f495ea4eeb..ecba5fcef201 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -324,12 +324,8 @@ static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
         /*
          * Need to allocate a group. Allocation of group also needs allocation
          * of per cpu stats which in-turn takes a mutex() and can block. Hence
-         * we need to drop rcu lock and queue_lock before we call alloc
-         *
-         * Take the request queue reference to make sure queue does not
-         * go away once we return from allocation.
+         * we need to drop rcu lock and queue_lock before we call alloc.
          */
-        blk_get_queue(q);
         rcu_read_unlock();
         spin_unlock_irq(q->queue_lock);
 
@@ -339,13 +335,11 @@ static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
          * dead
          */
         if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
-                blk_put_queue(q);
                 if (tg)
                         kfree(tg);
 
                 return ERR_PTR(-ENODEV);
         }
-        blk_put_queue(q);
 
         /* Group allocated and queue is still alive. take the lock */
         spin_lock_irq(q->queue_lock);