iommu/amd: Use trylock to aquire bitmap_lock

First search for a non-contended aperture with trylock
before spinning.

Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 84c7da1..eed355c 100644 (file)
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1542,7 +1542,8 @@ static dma_addr_t dma_ops_aperture_alloc(struct dma_ops_domain *dom,
                                         unsigned long pages,
                                         unsigned long dma_mask,
                                         unsigned long boundary_size,
-                                        unsigned long align_mask)
+                                        unsigned long align_mask,
+                                        bool trylock)
 {
        unsigned long offset, limit, flags;
        dma_addr_t address;
@@ -1552,7 +1553,13 @@ static dma_addr_t dma_ops_aperture_alloc(struct dma_ops_domain *dom,
        limit  = iommu_device_max_index(APERTURE_RANGE_PAGES, offset,
                                        dma_mask >> PAGE_SHIFT);
 
-       spin_lock_irqsave(&range->bitmap_lock, flags);
+       if (trylock) {
+               if (!spin_trylock_irqsave(&range->bitmap_lock, flags))
+                       return -1;
+       } else {
+               spin_lock_irqsave(&range->bitmap_lock, flags);
+       }
+
        address = iommu_area_alloc(range->bitmap, limit, range->next_bit,
                                   pages, offset, boundary_size, align_mask);
        if (address == -1) {
@@ -1584,12 +1591,14 @@ static unsigned long dma_ops_area_alloc(struct device *dev,
 {
        unsigned long boundary_size, mask;
        unsigned long address = -1;
+       bool first = true;
        u32 start, i;
 
        preempt_disable();
 
        mask = dma_get_seg_boundary(dev);
 
+again:
        start = this_cpu_read(*dom->next_index);
 
        /* Sanity check - is it really necessary? */
@@ -1614,7 +1623,7 @@ static unsigned long dma_ops_area_alloc(struct device *dev,
 
                address = dma_ops_aperture_alloc(dom, range, pages,
                                                 dma_mask, boundary_size,
-                                                align_mask);
+                                                align_mask, first);
                if (address != -1) {
                        address = range->offset + (address << PAGE_SHIFT);
                        this_cpu_write(*dom->next_index, index);
@@ -1622,6 +1631,11 @@ static unsigned long dma_ops_area_alloc(struct device *dev,
                }
        }
 
+       if (address == -1 && first) {
+               first = false;
+               goto again;
+       }
+
        preempt_enable();
 
        return address;