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Subject[PATCH 5/6] swiotlb: share more code between map_page and map_sg
Date
Refactor all the common code into what previously was map_single, which
is now renamed to __swiotlb_map_page. This also improves the map_sg
error handling and diagnostics to match the map_page ones.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
lib/swiotlb.c | 114 +++++++++++++++++++++++---------------------------
1 file changed, 53 insertions(+), 61 deletions(-)

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 8333277d1cd1..5becc2fc680a 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -595,21 +595,47 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
/*
* Allocates bounce buffer and returns its physical address.
*/
-static phys_addr_t
-map_single(struct device *hwdev, phys_addr_t phys, size_t size,
- enum dma_data_direction dir, unsigned long attrs)
+static int
+__swiotlb_map_page(struct device *dev, phys_addr_t phys, size_t size,
+ enum dma_data_direction dir, unsigned long attrs,
+ dma_addr_t *dma_addr)
{
- dma_addr_t start_dma_addr;
-
- if (swiotlb_force == SWIOTLB_NO_FORCE) {
- dev_warn_ratelimited(hwdev, "Cannot do DMA to address %pa\n",
- &phys);
- return SWIOTLB_MAP_ERROR;
+ phys_addr_t map_addr;
+
+ if (WARN_ON_ONCE(dir == DMA_NONE))
+ return -EINVAL;
+ *dma_addr = phys_to_dma(dev, phys);
+
+ switch (swiotlb_force) {
+ case SWIOTLB_NO_FORCE:
+ dev_warn_ratelimited(dev,
+ "swiotlb: force disabled for address %pa\n", &phys);
+ return -EOPNOTSUPP;
+ case SWIOTLB_NORMAL:
+ /* can we address the memory directly? */
+ if (dma_capable(dev, *dma_addr, size))
+ return 0;
+ break;
+ case SWIOTLB_FORCE:
+ break;
}

- start_dma_addr = __phys_to_dma(hwdev, io_tlb_start);
- return swiotlb_tbl_map_single(hwdev, start_dma_addr, phys, size,
- dir, attrs);
+ trace_swiotlb_bounced(dev, *dma_addr, size, swiotlb_force);
+ map_addr = swiotlb_tbl_map_single(dev, __phys_to_dma(dev, io_tlb_start),
+ phys, size, dir, attrs);
+ if (unlikely(map_addr == SWIOTLB_MAP_ERROR))
+ return -ENOMEM;
+
+ /* Ensure that the address returned is DMA'ble */
+ *dma_addr = __phys_to_dma(dev, map_addr);
+ if (unlikely(!dma_capable(dev, *dma_addr, size))) {
+ dev_err_ratelimited(dev,
+ "DMA: swiotlb buffer not addressable.\n");
+ swiotlb_tbl_unmap_single(dev, map_addr, size, dir,
+ attrs | DMA_ATTR_SKIP_CPU_SYNC);
+ return -EINVAL;
+ }
+ return 0;
}

/*
@@ -775,35 +801,12 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
enum dma_data_direction dir,
unsigned long attrs)
{
- phys_addr_t map, phys = page_to_phys(page) + offset;
- dma_addr_t dev_addr = phys_to_dma(dev, phys);
-
- BUG_ON(dir == DMA_NONE);
- /*
- * If the address happens to be in the device's DMA window,
- * we can safely return the device addr and not worry about bounce
- * buffering it.
- */
- if (dma_capable(dev, dev_addr, size) && swiotlb_force != SWIOTLB_FORCE)
- return dev_addr;
+ dma_addr_t dma_addr;

- trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
-
- /* Oh well, have to allocate and map a bounce buffer. */
- map = map_single(dev, phys, size, dir, attrs);
- if (map == SWIOTLB_MAP_ERROR)
+ if (unlikely(__swiotlb_map_page(dev, page_to_phys(page) + offset, size,
+ dir, attrs, &dma_addr) < 0))
return __phys_to_dma(dev, io_tlb_overflow_buffer);
-
- dev_addr = __phys_to_dma(dev, map);
-
- /* Ensure that the address returned is DMA'ble */
- if (dma_capable(dev, dev_addr, size))
- return dev_addr;
-
- attrs |= DMA_ATTR_SKIP_CPU_SYNC;
- swiotlb_tbl_unmap_single(dev, map, size, dir, attrs);
-
- return __phys_to_dma(dev, io_tlb_overflow_buffer);
+ return dma_addr;
}

/*
@@ -894,37 +897,26 @@ swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr,
* same here.
*/
int
-swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems,
+swiotlb_map_sg_attrs(struct device *dev, struct scatterlist *sgl, int nelems,
enum dma_data_direction dir, unsigned long attrs)
{
struct scatterlist *sg;
int i;

- BUG_ON(dir == DMA_NONE);
-
for_each_sg(sgl, sg, nelems, i) {
- phys_addr_t paddr = sg_phys(sg);
- dma_addr_t dev_addr = phys_to_dma(hwdev, paddr);
-
- if (swiotlb_force == SWIOTLB_FORCE ||
- !dma_capable(hwdev, dev_addr, sg->length)) {
- phys_addr_t map = map_single(hwdev, sg_phys(sg),
- sg->length, dir, attrs);
- if (map == SWIOTLB_MAP_ERROR) {
- /* Don't panic here, we expect map_sg users
- to do proper error handling. */
- attrs |= DMA_ATTR_SKIP_CPU_SYNC;
- swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir,
- attrs);
- sg_dma_len(sgl) = 0;
- return 0;
- }
- sg->dma_address = __phys_to_dma(hwdev, map);
- } else
- sg->dma_address = dev_addr;
+ if (unlikely(__swiotlb_map_page(dev, sg_phys(sg), sg->length,
+ dir, attrs, &sg->dma_address) < 0))
+ goto out_error;
sg_dma_len(sg) = sg->length;
}
+
return nelems;
+
+out_error:
+ swiotlb_unmap_sg_attrs(dev, sgl, i, dir,
+ attrs | DMA_ATTR_SKIP_CPU_SYNC);
+ sg_dma_len(sgl) = 0;
+ return 0;
}

/*
--
2.17.0
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