dma-mapping: simplify dma_init_coherent_memory

Return the allocated dma_coherent_mem structure, set the
use_dma_pfn_offset and print the failure warning inside of
dma_init_coherent_memory instead of leaving that to the callers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Dillon Min <dillon.minfei@gmail.com>

kernel/dma/coherent.c

@@ -37,51 +37,44 @@ static inline dma_addr_t dma_get_device_base(struct device *dev,
 	return mem->device_base;
 }
 
-static int dma_init_coherent_memory(phys_addr_t phys_addr,
-		dma_addr_t device_addr, size_t size,
-		struct dma_coherent_mem **mem)
+static struct dma_coherent_mem *dma_init_coherent_memory(phys_addr_t phys_addr,
+		dma_addr_t device_addr, size_t size, bool use_dma_pfn_offset)
 {
-	struct dma_coherent_mem *dma_mem = NULL;
-	void *mem_base = NULL;
+	struct dma_coherent_mem *dma_mem;
 	int pages = size >> PAGE_SHIFT;
 	int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
-	int ret;
+	void *mem_base;
 
-	if (!size) {
-		ret = -EINVAL;
-		goto out;
-	}
+	if (!size)
+		return ERR_PTR(-EINVAL);
 
 	mem_base = memremap(phys_addr, size, MEMREMAP_WC);
-	if (!mem_base) {
-		ret = -EINVAL;
-		goto out;
-	}
+	if (!mem_base)
+		return ERR_PTR(-EINVAL);
+
 	dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
-	if (!dma_mem) {
-		ret = -ENOMEM;
-		goto out;
-	}
+	if (!dma_mem)
+		goto out_unmap_membase;
 	dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
-	if (!dma_mem->bitmap) {
-		ret = -ENOMEM;
-		goto out;
-	}
+	if (!dma_mem->bitmap)
+		goto out_free_dma_mem;
 
 	dma_mem->virt_base = mem_base;
 	dma_mem->device_base = device_addr;
 	dma_mem->pfn_base = PFN_DOWN(phys_addr);
 	dma_mem->size = pages;
+	dma_mem->use_dev_dma_pfn_offset = use_dma_pfn_offset;
 	spin_lock_init(&dma_mem->spinlock);
 
-	*mem = dma_mem;
-	return 0;
+	return dma_mem;
 
-out:
+out_free_dma_mem:
 	kfree(dma_mem);
-	if (mem_base)
-		memunmap(mem_base);
-	return ret;
+out_unmap_membase:
+	memunmap(mem_base);
+	pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %zd MiB\n",
+		&phys_addr, size / SZ_1M);
+	return ERR_PTR(-ENOMEM);
 }
 
 static void dma_release_coherent_memory(struct dma_coherent_mem *mem)
@@ -130,9 +123,9 @@ int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 	struct dma_coherent_mem *mem;
 	int ret;
 
-	ret = dma_init_coherent_memory(phys_addr, device_addr, size, &mem);
-	if (ret)
-		return ret;
+	mem = dma_init_coherent_memory(phys_addr, device_addr, size, false);
+	if (IS_ERR(mem))
+		return PTR_ERR(mem);
 
 	ret = dma_assign_coherent_memory(dev, mem);
 	if (ret)
@@ -319,21 +312,16 @@ static struct reserved_mem *dma_reserved_default_memory __initdata;
 
 static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
 {
-	struct dma_coherent_mem *mem = rmem->priv;
-	int ret;
-
-	if (!mem) {
-		ret = dma_init_coherent_memory(rmem->base, rmem->base,
-					       rmem->size, &mem);
-		if (ret) {
-			pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
-				&rmem->base, (unsigned long)rmem->size / SZ_1M);
-			return ret;
-		}
+	if (!rmem->priv) {
+		struct dma_coherent_mem *mem;
+
+		mem = dma_init_coherent_memory(rmem->base, rmem->base,
+					       rmem->size, true);
+		if (IS_ERR(mem))
+			return PTR_ERR(mem);
+		rmem->priv = mem;
 	}
-	mem->use_dev_dma_pfn_offset = true;
-	rmem->priv = mem;
-	dma_assign_coherent_memory(dev, mem);
+	dma_assign_coherent_memory(dev, rmem->priv);
 	return 0;
 }