From: Alexander Gordeev <agordeev@redhat.com>
Date: Tue, 17 Jun 2014 20:37:23 +0000 (+0200)
Subject: blk-mq: bitmap tag: fix races in bt_get() function
X-Git-Tag: omap-for-v3.17/soc-cleanup~74^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=86fb5c56cfa26de5e91c9a50e2767a695dff366e;p=pandora-kernel.git

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>
---

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