From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Date: Tue, 18 Apr 2006 07:44:06 +0000 (+0200)
Subject: [PATCH 1/2] iosched: fix typo and barrier()
X-Git-Tag: v2.6.17-rc2~15^2~2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fba822722e3f9d438fca8fd9541d7ddd447d7a48;p=pandora-kernel.git

[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>
---

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