tree c50ed0dd313e7fcffddd021639473f001fcf8b05
parent 2472892a3ce17b177cc0d8099a6391949c75abf2
author Akinobu Mita <akinobu.mita@gmail.com> 1208764266 +0200
committer Jens Axboe <jens.axboe@oracle.com> 1208764266 +0200

block: fix blk_register_queue() return value

blk_register_queue() returns -ENXIO when queue->request_fn is NULL.  But there
are some block drivers that call blk_register_queue() via add_disk() with
queue->request_fn == NULL.  (For example, brd, loop)

Although no one checks return value of blk_register_queue(), this patch makes
it return 0 instead of -ENXIO when queue->request_fn is NULL,

Also this patch adds warning when blk_register_queue() and
blk_unregister_queue() are called with queue == NULL rather than ignore
invalid usage silently.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>