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| author | Mike Waychison <mikew@google.com> | 2006-04-21 09:43:25 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2006-05-01 12:03:42 -0700 |
| commit | c89ce82c2d942daacc7d7f5d3efafe7dba70bd23 (patch) | |
| tree | a497456b81e016a4893a2d3927475eb282b75ef9 | |
| parent | 355bd3d4ea761a66880088ac2d0c5c95866df4a6 (diff) | |
| download | lwn-c89ce82c2d942daacc7d7f5d3efafe7dba70bd23.tar.gz lwn-c89ce82c2d942daacc7d7f5d3efafe7dba70bd23.zip | |
[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: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | arch/x86_64/kernel/pci-gart.c | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/arch/x86_64/kernel/pci-gart.c b/arch/x86_64/kernel/pci-gart.c index 0c3f052ba6ce..b9dbe3ce967c 100644 --- a/arch/x86_64/kernel/pci-gart.c +++ b/arch/x86_64/kernel/pci-gart.c @@ -114,10 +114,6 @@ static unsigned long alloc_iommu(int size) static void free_iommu(unsigned long offset, int size) { unsigned long flags; - if (size == 1) { - clear_bit(offset, iommu_gart_bitmap); - return; - } spin_lock_irqsave(&iommu_bitmap_lock, flags); __clear_bit_string(iommu_gart_bitmap, offset, size); spin_unlock_irqrestore(&iommu_bitmap_lock, flags); |