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| author | Bart Van Assche <bvanassche@acm.org> | 2014-12-09 16:58:11 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2014-12-09 09:07:14 -0700 |
| commit | 9e98e9d7cf6e9d2ec1cce45e8d5ccaf3f9b386f3 (patch) | |
| tree | 9bf1d9e63d5f19088be8a6bfe8e141f6ab887bb4 /block/blk-mq-tag.c | |
| parent | 45a9c9d909b24c6ad0e28a7946e7486e73010319 (diff) | |
| download | linux-0-day-9e98e9d7cf6e9d2ec1cce45e8d5ccaf3f9b386f3.tar.gz linux-0-day-9e98e9d7cf6e9d2ec1cce45e8d5ccaf3f9b386f3.tar.xz | |
blk-mq: Avoid that __bt_get_word() wraps multiple times
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>
Cc: <stable@vger.kernel.org> # v3.13+
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/blk-mq-tag.c')
| -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 bab4bff15f428..0f5e22a7971fb 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; } |