[PATCH] nsc-ircc driver crashes on shutdown

From: Petr Vandrovec <vandrove@vc.cvut.cz>

bk-dma-decleare-coherent-memory patch adds a requirement for
dma_free_coherent that dev cannot be NULL...  But it can (nsc-ircc has no
suitable dev) and as dma_alloc_coherent allows NULL dev, dma_free_coherent
should allow it too IMHO.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

arch/i386/kernel/pci-dma.c

@@ -58,7 +58,7 @@ void *dma_alloc_coherent(struct device *dev, size_t size,
 void dma_free_coherent(struct device *dev, size_t size,
 			 void *vaddr, dma_addr_t dma_handle)
 {
-	struct dma_coherent_mem *mem = dev->dma_mem;
+	struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
 	int order = get_order(size);
 	
 	if (mem && vaddr >= mem->virt_base && vaddr < (mem->virt_base + (mem->size << PAGE_SHIFT))) {