tree 05fc35428f61fb6b66726e3aae03ce9187212c21
parent a9a5cd5d2a57fb76dbae2115450f777b69beccf7
author OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> 1145346246 +0200
committer Jens Axboe <axboe@suse.de> 1145346246 +0200

[PATCH 1/2] iosched: fix typo and barrier()

On rmmod path, cfq/as waits to make sure all io-contexts was
freed. However, it's using complete(), not wait_for_completion().

I think barrier() is not enough in here. To avoid the following case,
this patch replaces barrier() with smb_wmb().

	cpu0			visibility			cpu1
	                [ioc_gnone=NULL,ioc_count=1]

ioc_gnone = &all_gone		NULL,ioc_count=1
atomic_read(&ioc_count)		NULL,ioc_count=1
wait_for_completion()		NULL,ioc_count=0	atomic_sub_and_test()
				NULL,ioc_count=0	if ( && ioc_gone)
						    [ioc_gone==NULL,
						    so doesn't call complete()]
			   &all_gone,ioc_count=0

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Jens Axboe <axboe@suse.de>