tree 656bbfa7104e065f0da8eac0c14b62ba1c088214
parent 0fe23479577124bd2687e6783e39fa0fa4c28005
author Jens Axboe <axboe@kernel.dk> 1158863842 +0200
committer Jens Axboe <axboe@nelson.home.kernel.dk> 1159642354 +0200

[PATCH] blk_queue_start_tag() shared map race fix

If we share the tag map between two or more queues, then we cannot
use __set_bit() to set the bit. In fact we need to make sure we
atomically acquire this tag, so loop using test_and_set_bit() to
protect from that.

Noticed by Mike Christie <michaelc@cs.wisc.edu>

Signed-off-by: Jens Axboe <axboe@kernel.dk>