[Xen-changelog] Fix dma_map_single to work correctly with mutli-page buffers.

[Xen patchbot -2.0-testing <patchbot-2.0-testing@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID f5c64bb5ed7433e2b0ee698d982effb7119866b3
# Parent  ae9fd9d9628fc9e76e3b7681fa75c1280408bc66

Fix dma_map_single to work correctly with mutli-page buffers.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>

diff -r ae9fd9d9628f -r f5c64bb5ed74 
linux-2.6.11-xen-sparse/arch/xen/i386/kernel/pci-dma.c
--- a/linux-2.6.11-xen-sparse/arch/xen/i386/kernel/pci-dma.c    Fri Jul  1 
15:42:58 2005
+++ b/linux-2.6.11-xen-sparse/arch/xen/i386/kernel/pci-dma.c    Fri Jul  8 
12:55:56 2005
@@ -232,4 +232,121 @@
 }
 EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
 
+static LIST_HEAD(dma_map_head);
+static DEFINE_SPINLOCK(dma_map_lock);
+struct dma_map_entry {
+       struct list_head list;
+       dma_addr_t dma;
+       void *bounce, *host;
+};
+
+dma_addr_t
+dma_map_single(struct device *dev, void *ptr, size_t size,
+              enum dma_data_direction direction)
+{
+       struct dma_map_entry *ent;
+       void *bnc;
+       dma_addr_t dma;
+       unsigned long flags;
+
+       BUG_ON(direction == DMA_NONE);
+
+       /*
+        * Even if size is sub-page, the buffer may still straddle a page
+        * boundary. Take into account buffer start offset. All other calls are
+        * conservative and always search the dma_map list if it's non-empty.
+        */
+       if ((((unsigned int)ptr & ~PAGE_MASK) + size) <= PAGE_SIZE) {
+               dma = virt_to_bus(ptr);
+       } else {
+               BUG_ON((bnc = dma_alloc_coherent(dev, size, &dma, 0)) == NULL);
+               BUG_ON((ent = kmalloc(sizeof(*ent), GFP_KERNEL)) == NULL);
+               if (direction != DMA_FROM_DEVICE)
+                       memcpy(bnc, ptr, size);
+               ent->dma    = dma;
+               ent->bounce = bnc;
+               ent->host   = ptr;
+               spin_lock_irqsave(&dma_map_lock, flags);
+               list_add(&ent->list, &dma_map_head);
+               spin_unlock_irqrestore(&dma_map_lock, flags);
+       }
+
+       flush_write_buffers();
+       return dma;
+}
+EXPORT_SYMBOL(dma_map_single);
+
+void
+dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
+                enum dma_data_direction direction)
+{
+       struct dma_map_entry *ent;
+       unsigned long flags;
+
+       BUG_ON(direction == DMA_NONE);
+
+       /* Fast-path check: are there any multi-page DMA mappings? */
+       if (!list_empty(&dma_map_head)) {
+               spin_lock_irqsave(&dma_map_lock, flags);
+               list_for_each_entry ( ent, &dma_map_head, list ) {
+                       if (ent->dma == dma_addr) {
+                               list_del(&ent->list);
+                               break;
+                       }
+               }
+               spin_unlock_irqrestore(&dma_map_lock, flags);
+               if (&ent->list != &dma_map_head) {
+                       if (direction != DMA_TO_DEVICE)
+                               memcpy(ent->host, ent->bounce, size);
+                       dma_free_coherent(dev, size, ent->bounce, ent->dma);
+                       kfree(ent);
+               }
+       }
+}
+EXPORT_SYMBOL(dma_unmap_single);
+
+void
+dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle, size_t size,
+                       enum dma_data_direction direction)
+{
+       struct dma_map_entry *ent;
+       unsigned long flags;
+
+       /* Fast-path check: are there any multi-page DMA mappings? */
+       if (!list_empty(&dma_map_head)) {
+               spin_lock_irqsave(&dma_map_lock, flags);
+               list_for_each_entry ( ent, &dma_map_head, list )
+                       if (ent->dma == dma_handle)
+                               break;
+               spin_unlock_irqrestore(&dma_map_lock, flags);
+               if (&ent->list != &dma_map_head)
+                       if (direction != DMA_TO_DEVICE)
+                               memcpy(ent->host, ent->bounce, size);
+       }
+}
+EXPORT_SYMBOL(dma_sync_single_for_cpu);
+
+void
+dma_sync_single_for_device(struct device *dev, dma_addr_t dma_handle, size_t 
size,
+                           enum dma_data_direction direction)
+{
+       struct dma_map_entry *ent;
+       unsigned long flags;
+
+       /* Fast-path check: are there any multi-page DMA mappings? */
+       if (!list_empty(&dma_map_head)) {
+               spin_lock_irqsave(&dma_map_lock, flags);
+               list_for_each_entry ( ent, &dma_map_head, list )
+                       if (ent->dma == dma_handle)
+                               break;
+               spin_unlock_irqrestore(&dma_map_lock, flags);
+               if (&ent->list != &dma_map_head)
+                       if (direction != DMA_FROM_DEVICE)
+                               memcpy(ent->bounce, ent->host, size);
+       }
+
+       flush_write_buffers();
+}
+EXPORT_SYMBOL(dma_sync_single_for_device);
+
 #endif
diff -r ae9fd9d9628f -r f5c64bb5ed74 
linux-2.6.11-xen-sparse/include/asm-xen/asm-i386/dma-mapping.h
--- a/linux-2.6.11-xen-sparse/include/asm-xen/asm-i386/dma-mapping.h    Fri Jul 
 1 15:42:58 2005
+++ b/linux-2.6.11-xen-sparse/include/asm-xen/asm-i386/dma-mapping.h    Fri Jul 
 8 12:55:56 2005
@@ -16,21 +16,13 @@
 void dma_free_coherent(struct device *dev, size_t size,
                         void *vaddr, dma_addr_t dma_handle);
 
-static inline dma_addr_t
+extern dma_addr_t
 dma_map_single(struct device *dev, void *ptr, size_t size,
-              enum dma_data_direction direction)
-{
-       BUG_ON(direction == DMA_NONE);
-       flush_write_buffers();
-       return virt_to_bus(ptr);
-}
+              enum dma_data_direction direction);
 
-static inline void
+extern void
 dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
-                enum dma_data_direction direction)
-{
-       BUG_ON(direction == DMA_NONE);
-}
+                enum dma_data_direction direction);
 
 static inline int
 dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
@@ -73,24 +65,20 @@
        BUG_ON(direction == DMA_NONE);
 }
 
-static inline void
+extern void
 dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle, size_t size,
-                       enum dma_data_direction direction)
-{
-}
+                       enum dma_data_direction direction);
 
-static inline void
+extern void
 dma_sync_single_for_device(struct device *dev, dma_addr_t dma_handle, size_t 
size,
-                       enum dma_data_direction direction)
-{
-       flush_write_buffers();
-}
+                           enum dma_data_direction direction);
 
 static inline void
 dma_sync_single_range_for_cpu(struct device *dev, dma_addr_t dma_handle,
                              unsigned long offset, size_t size,
                              enum dma_data_direction direction)
 {
+       dma_sync_single_for_cpu(dev, dma_handle, size, direction);
 }
 
 static inline void
@@ -98,7 +86,7 @@
                                 unsigned long offset, size_t size,
                                 enum dma_data_direction direction)
 {
-       flush_write_buffers();
+       dma_sync_single_for_device(dev, dma_handle, size, direction);
 }
 
 static inline void

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