x86: retry allocation if failed

This patch puts in the code to retry allocation in case it fails. By its
own, it does not make much sense but making the code look like x86_64.
But later patches in this series will make we try to allocate from
zones other than DMA first, which will possibly fail.

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 29 insertions, 5 deletions

diff --git a/arch/x86/kernel/pci-dma_32.c b/arch/x86/kernel/pci-dma_32.c
index debe9119b724..11f100a5f034 100644
--- a/arch/x86/kernel/pci-dma_32.c
+++ b/arch/x86/kernel/pci-dma_32.c
@@ -76,6 +76,8 @@ void *dma_alloc_coherent(struct device *dev, size_t size,
         struct page *page;
         dma_addr_t bus;
         int order = get_order(size);
+        unsigned long dma_mask = 0;
+
         /* ignore region specifiers */
         gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
 
@@ -85,15 +87,37 @@ void *dma_alloc_coherent(struct device *dev, size_t size,
         if (!dev)
                 dev = &fallback_dev;
 
+        dma_mask = dev->coherent_dma_mask;
+        if (dma_mask == 0)
+                dma_mask = DMA_32BIT_MASK;
+
+ again:
         page = dma_alloc_pages(dev, gfp, order);
         if (page == NULL)
                 return NULL;
 
-        ret = page_address(page);
-        bus = page_to_phys(page);
-
-        memset(ret, 0, size);
-        *dma_handle = bus;
+        {
+                int high, mmu;
+                bus = page_to_phys(page);
+                ret = page_address(page);
+                high = (bus + size) >= dma_mask;
+                mmu = high;
+                if (force_iommu && !(gfp & GFP_DMA))
+                        mmu = 1;
+                else if (high) {
+                        free_pages((unsigned long)ret,
+                                   get_order(size));
+
+                        /* Don't use the 16MB ZONE_DMA unless absolutely
+                           needed. It's better to use remapping first. */
+                        if (dma_mask < DMA_32BIT_MASK && !(gfp & GFP_DMA)) {
+                                gfp = (gfp & ~GFP_DMA32) | GFP_DMA;
+                                goto again;
+                        }
+                }
+                memset(ret, 0, size);
+                *dma_handle = bus;
+        }
 
         return ret;
 }