From 5b20192727ef2c047343a043ee4fbda67e2beef4 Mon Sep 17 00:00:00 2001 From: Mike Waychison 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 Signed-off-by: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86_64/kernel/pci-gart.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/arch/x86_64/kernel/pci-gart.c b/arch/x86_64/kernel/pci-gart.c index a6c01e1..9d3d76c 100644 --- a/arch/x86_64/kernel/pci-gart.c +++ b/arch/x86_64/kernel/pci-gart.c @@ -112,10 +112,6 @@ 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); -- 2.7.4