[tip:x86/dma] swiotlb: Make swiotlb_{alloc,free}_buffer depend on CONFIG_DMA_DIRECT_OPS

[tip-bot for Christoph Hellwig]

Commit-ID:  0803e6051c1562e1525c3e044313390bf8b35c2b
Gitweb:     https://git.kernel.org/tip/0803e6051c1562e1525c3e044313390bf8b35c2b
Author:     Christoph Hellwig <hch@xxxxxx>
AuthorDate: Fri, 23 Mar 2018 18:49:30 +0100
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Fri, 23 Mar 2018 20:15:38 +0100

swiotlb: Make swiotlb_{alloc,free}_buffer depend on CONFIG_DMA_DIRECT_OPS

Otherwise this causes unused symbol warnings for configs that build
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@xxxxxxxxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: konrad.wilk@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20180323174930.17767-1-hch@xxxxxx
---
 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,