diff options
| author | Bart Van Assche <bvanassche@acm.org> | 2014-12-09 16:58:11 +0100 |
|---|---|---|
| committer | Luis Henriques <luis.henriques@canonical.com> | 2015-01-15 10:43:41 +0000 |
| commit | 87a13a346316f60771cad304cbf0c85b5e6f3c04 (patch) | |
| tree | a785324dccf1956da34ba480fb07067e216a69fa /block | |
| parent | 294d749602b8db3e9a3981d238e7b01498099daf (diff) | |
blk-mq: Avoid that __bt_get_word() wraps multiple times
commit 9e98e9d7cf6e9d2ec1cce45e8d5ccaf3f9b386f3 upstream.
If __bt_get_word() is called with last_tag != 0, if the first
find_next_zero_bit() fails, if after wrap-around the
test_and_set_bit() call fails and find_next_zero_bit() succeeds,
if the next test_and_set_bit() call fails and subsequently
find_next_zero_bit() does not find a zero bit, then another
wrap-around will occur. Avoid this by introducing an additional
local variable.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Robert Elliott <elliott@hp.com>
Cc: Ming Lei <ming.lei@canonical.com>
Cc: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-mq-tag.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index 74a4168ea34e..a1bc33974fc4 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -137,6 +137,7 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx, static int __bt_get_word(struct blk_align_bitmap *bm, unsigned int last_tag) { int tag, org_last_tag, end; + bool wrap = last_tag != 0; org_last_tag = last_tag; end = bm->depth; @@ -148,8 +149,9 @@ restart: * We started with an offset, start from 0 to * exhaust the map. */ - if (org_last_tag && last_tag) { - end = last_tag; + if (wrap) { + wrap = false; + end = org_last_tag; last_tag = 0; goto restart; } |