From 5b20192727ef2c047343a043ee4fbda67e2beef4 Mon Sep 17 00:00:00 2001
From: Mike Waychison <mikew@google.com>
Date: Sat, 22 Apr 2006 02:36:06 -0700
Subject: [PATCH] [PATCH] x86_64: Fix a race in the free_iommu path

We do this by removing a micro-optimization that tries to avoid grabbing
the iommu_bitmap_lock spinlock and using a bus-locked operation.

This still races with other simultaneous alloc_iommu or free_iommu(size >
1) which both use bus-unlocked operations.

The end result of this race is eventually ending up with an
iommu_gart_bitmap that has bits errornously set all over, making large
contiguous iommu space allocations fail with 'PCI-DMA: Out of IOMMU space'.

Signed-off-by: Mike Waychison <mikew@google.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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