tree da9f94abed8dac7479507601694d9276b2dbaf28
parent 040c928c47b591d1cd9977cd6431cae213528b45
author Nick Piggin <nickpiggin@yahoo.com.au> 1119510532 -0700
committer Linus Torvalds <torvalds@ppc970.osdl.org> 1119545116 -0700

[PATCH] blk: no memory barrier

This memory barrier is not needed because the waitqueue will only get waiters
on it in the following situations:

rq->count has exceeded the threshold - however all manipulations of ->count
are performed under the runqueue lock, and so we will correctly pick up any
waiter.

Memory allocation for the request fails.  In this case, there is no additional
help provided by the memory barrier.  We are guaranteed to eventually wake up
waiters because the request allocation mempool guarantees that if the mem
allocation for a request fails, there must be some requests in flight.  They
will wake up waiters when they are retired.

Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Jens Axboe <axboe@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>