[PATCH] swiotlb: swiotlb_{alloc, free}_buffer should depend on CONFIG_DMA_DIRECT_OPS

[Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>]

Otherwise we might get unused symbol warnings for configs that built
swiotlb.c only for use by xen-swiotlb.c and that don't otherwise select
CONFIG_DMA_DIRECT_OPS, which is possible on arm.

Fixes: 16e73adbca76 ("dma/swiotlb: Remove swiotlb_{alloc,free}_coherent()")
Reported-by: Stephen Rothwell <sfr-3FnU+UHB4dNDw9hX6IcOSA@public.gmane.org>
Signed-off-by: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
---
 lib/swiotlb.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 15954b86f09e..47aeb04c1997 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -692,6 +692,7 @@ void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
 	}
 }
 
+#ifdef CONFIG_DMA_DIRECT_OPS
 static inline bool dma_coherent_ok(struct device *dev, dma_addr_t addr,
 		size_t size)
 {
@@ -763,6 +764,7 @@ static bool swiotlb_free_buffer(struct device *dev, size_t size,
 				 DMA_ATTR_SKIP_CPU_SYNC);
 	return true;
 }
+#endif
 
 static void
 swiotlb_full(struct device *dev, size_t size, enum dma_data_direction dir,
-- 
2.14.2