dma: compile-out DMA sync op calls when not used

Some platforms do have DMA, but DMA there is always direct and coherent.
Currently, even on such platforms DMA sync operations are compiled and
called.
Add a new hidden Kconfig symbol, DMA_NEED_SYNC, and set it only when
either sync operations are needed or there is DMA ops or swiotlb
or DMA debug is enabled. Compile global dma_sync_*() and dma_need_sync()
only when it's set, otherwise provide empty inline stubs.
The change allows for future optimizations of DMA sync calls depending
on runtime conditions.

Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 4a658de44ee92e8e090e6bb08a6cc45590f82bfe..a569b56b25e2c62ca8cd9ac93d17be4d426ec6af 100644 (file)
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -117,14 +117,6 @@ dma_addr_t dma_map_resource(struct device *dev, phys_addr_t phys_addr,
                size_t size, enum dma_data_direction dir, unsigned long attrs);
 void dma_unmap_resource(struct device *dev, dma_addr_t addr, size_t size,
                enum dma_data_direction dir, unsigned long attrs);
-void dma_sync_single_for_cpu(struct device *dev, dma_addr_t addr, size_t size,
-               enum dma_data_direction dir);
-void dma_sync_single_for_device(struct device *dev, dma_addr_t addr,
-               size_t size, enum dma_data_direction dir);
-void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
-                   int nelems, enum dma_data_direction dir);
-void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
-                      int nelems, enum dma_data_direction dir);
 void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle,
                gfp_t flag, unsigned long attrs);
 void dma_free_attrs(struct device *dev, size_t size, void *cpu_addr,
@@ -147,7 +139,6 @@ u64 dma_get_required_mask(struct device *dev);
 bool dma_addressing_limited(struct device *dev);
 size_t dma_max_mapping_size(struct device *dev);
 size_t dma_opt_mapping_size(struct device *dev);
-bool dma_need_sync(struct device *dev, dma_addr_t dma_addr);
 unsigned long dma_get_merge_boundary(struct device *dev);
 struct sg_table *dma_alloc_noncontiguous(struct device *dev, size_t size,
                enum dma_data_direction dir, gfp_t gfp, unsigned long attrs);
@@ -195,22 +186,6 @@ static inline void dma_unmap_resource(struct device *dev, dma_addr_t addr,
                size_t size, enum dma_data_direction dir, unsigned long attrs)
 {
 }
-static inline void dma_sync_single_for_cpu(struct device *dev, dma_addr_t addr,
-               size_t size, enum dma_data_direction dir)
-{
-}
-static inline void dma_sync_single_for_device(struct device *dev,
-               dma_addr_t addr, size_t size, enum dma_data_direction dir)
-{
-}
-static inline void dma_sync_sg_for_cpu(struct device *dev,
-               struct scatterlist *sg, int nelems, enum dma_data_direction dir)
-{
-}
-static inline void dma_sync_sg_for_device(struct device *dev,
-               struct scatterlist *sg, int nelems, enum dma_data_direction dir)
-{
-}
 static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
        return -ENOMEM;
@@ -277,10 +252,6 @@ static inline size_t dma_opt_mapping_size(struct device *dev)
 {
        return 0;
 }
-static inline bool dma_need_sync(struct device *dev, dma_addr_t dma_addr)
-{
-       return false;
-}
 static inline unsigned long dma_get_merge_boundary(struct device *dev)
 {
        return 0;
@@ -310,6 +281,39 @@ static inline int dma_mmap_noncontiguous(struct device *dev,
 }
 #endif /* CONFIG_HAS_DMA */
 
+#if defined(CONFIG_HAS_DMA) && defined(CONFIG_DMA_NEED_SYNC)
+void dma_sync_single_for_cpu(struct device *dev, dma_addr_t addr, size_t size,
+               enum dma_data_direction dir);
+void dma_sync_single_for_device(struct device *dev, dma_addr_t addr,
+               size_t size, enum dma_data_direction dir);
+void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
+               int nelems, enum dma_data_direction dir);
+void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
+               int nelems, enum dma_data_direction dir);
+bool dma_need_sync(struct device *dev, dma_addr_t dma_addr);
+#else /* !CONFIG_HAS_DMA || !CONFIG_DMA_NEED_SYNC */
+static inline void dma_sync_single_for_cpu(struct device *dev, dma_addr_t addr,
+               size_t size, enum dma_data_direction dir)
+{
+}
+static inline void dma_sync_single_for_device(struct device *dev,
+               dma_addr_t addr, size_t size, enum dma_data_direction dir)
+{
+}
+static inline void dma_sync_sg_for_cpu(struct device *dev,
+               struct scatterlist *sg, int nelems, enum dma_data_direction dir)
+{
+}
+static inline void dma_sync_sg_for_device(struct device *dev,
+               struct scatterlist *sg, int nelems, enum dma_data_direction dir)
+{
+}
+static inline bool dma_need_sync(struct device *dev, dma_addr_t dma_addr)
+{
+       return false;
+}
+#endif /* !CONFIG_HAS_DMA || !CONFIG_DMA_NEED_SYNC */
+
 struct page *dma_alloc_pages(struct device *dev, size_t size,
                dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp);
 void dma_free_pages(struct device *dev, size_t size, struct page *page,

diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
index d62f5957f36be7601d99ffc2491a95473967f912..c06e56be0ca1e69bbdc52bb99c8c938595176c8b 100644 (file)
--- a/kernel/dma/Kconfig
+++ b/kernel/dma/Kconfig
@@ -107,6 +107,11 @@ config DMA_BOUNCE_UNALIGNED_KMALLOC
        bool
        depends on SWIOTLB
 
+config DMA_NEED_SYNC
+       def_bool ARCH_HAS_SYNC_DMA_FOR_DEVICE || ARCH_HAS_SYNC_DMA_FOR_CPU || \
+                ARCH_HAS_SYNC_DMA_FOR_CPU_ALL || DMA_API_DEBUG || DMA_OPS || \
+                SWIOTLB
+
 config DMA_RESTRICTED_POOL
        bool "DMA Restricted Pool"
        depends on OF && OF_RESERVED_MEM && SWIOTLB

diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 58db8fd70471a197c3fcd1d745b4fbc864b6634c..c78b78e95a26343f01eaeb0e3e7a38c1ddd49f60 100644 (file)
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -329,6 +329,7 @@ void dma_unmap_resource(struct device *dev, dma_addr_t addr, size_t size,
 }
 EXPORT_SYMBOL(dma_unmap_resource);
 
+#ifdef CONFIG_DMA_NEED_SYNC
 void dma_sync_single_for_cpu(struct device *dev, dma_addr_t addr, size_t size,
                enum dma_data_direction dir)
 {
@@ -385,6 +386,17 @@ void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 }
 EXPORT_SYMBOL(dma_sync_sg_for_device);
 
+bool dma_need_sync(struct device *dev, dma_addr_t dma_addr)
+{
+       const struct dma_map_ops *ops = get_dma_ops(dev);
+
+       if (dma_map_direct(dev, ops))
+               return dma_direct_need_sync(dev, dma_addr);
+       return ops->sync_single_for_cpu || ops->sync_single_for_device;
+}
+EXPORT_SYMBOL_GPL(dma_need_sync);
+#endif /* CONFIG_DMA_NEED_SYNC */
+
 /*
  * The whole dma_get_sgtable() idea is fundamentally unsafe - it seems
  * that the intention is to allow exporting memory allocated via the
@@ -841,16 +853,6 @@ size_t dma_opt_mapping_size(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(dma_opt_mapping_size);
 
-bool dma_need_sync(struct device *dev, dma_addr_t dma_addr)
-{
-       const struct dma_map_ops *ops = get_dma_ops(dev);
-
-       if (dma_map_direct(dev, ops))
-               return dma_direct_need_sync(dev, dma_addr);
-       return ops->sync_single_for_cpu || ops->sync_single_for_device;
-}
-EXPORT_SYMBOL_GPL(dma_need_sync);
-
 unsigned long dma_get_merge_boundary(struct device *dev)
 {
        const struct dma_map_ops *ops = get_dma_ops(dev);