tree da76443281fb15c54d56400b25ff9279e0b9e33e
parent 2971c35f35886b87af54675313a2afef937c1b0c
author Alexander Gordeev <agordeev@redhat.com> 1403037443 +0200
committer Jens Axboe <axboe@fb.com> 1403068388 -0700

blk-mq: bitmap tag: fix races in bt_get() function

This update fixes few issues in bt_get() function:

- list_empty(&wait.task_list) check is not protected;

- was_empty check is always true which results in *every* thread
  entering the loop resets bt_wait_state::wait_cnt counter rather
  than every bt->wake_cnt'th thread;

- 'bt_wait_state::wait_cnt' counter update is redundant, since
  it also gets reset in bt_clear_tag() function;

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ming Lei <tom.leiming@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>