Re: [GIT PULL] dma-mapping updates for Linux 6.12

[Christoph Hellwig <hch@infradead.org>]

On Sun, Sep 22, 2024 at 02:56:57PM +0800, Xi Ruoyao wrote:
> With SND disabled, b5c58b2fdc427e7958412ecb2de2804a1f7c1572 boots fine
> (no oops), but the camera does not work. 
> f69e342eec008e1bab772d3963c3dd9979293e13 boots fine and the camera works
> fine.
> 
> So the first bad commit is b5c58b2fdc427e7958412ecb2de2804a1f7c1572.

Thanks a lot for the bisection!

I took a quitck look what is special in the intersection of uvcvideo
and that commit, and what springs to meind is that
uvcvideo is one of the very few users of dma_alloc_noncontiguous, and
while that and the free call for it got converted correctly, the
conversion was missed for the vmap and mmap callbacks.

Can you test the fix below?

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 3672d619bcb691..2a9fa0c8cc00fe 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1038,6 +1038,21 @@ static void *iommu_dma_alloc_remap(struct device *dev, size_t size,
 	return NULL;
 }
 
+/*
+ * This is the actual return value from the iommu_dma_alloc_noncontiguous.
+ *
+ * The users of the DMA API should only care about the sg_table, but to make
+ * the DMA-API internal vmaping and freeing easier we stash away the page
+ * array as well (except for the fallback case).  This can go away any time,
+ * e.g. when a vmap-variant that takes a scatterlist comes along.
+ */
+struct dma_sgt_handle {
+	struct sg_table sgt;
+	struct page **pages;
+};
+#define sgt_handle(sgt) \
+	container_of((sgt), struct dma_sgt_handle, sgt)
+
 struct sg_table *iommu_dma_alloc_noncontiguous(struct device *dev, size_t size,
 	       enum dma_data_direction dir, gfp_t gfp, unsigned long attrs)
 {
@@ -1066,6 +1081,24 @@ void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
 	kfree(sh);
 }
 
+void *iommu_dma_vmap_noncontiguous(struct device *dev, size_t size,
+		struct sg_table *sgt)
+{
+	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+	return vmap(sgt_handle(sgt)->pages, count, VM_MAP, PAGE_KERNEL);
+}
+
+int iommu_dma_mmap_noncontiguous(struct device *dev, struct vm_area_struct *vma,
+		size_t size, struct sg_table *sgt)
+{
+	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+	if (vma->vm_pgoff >= count || vma_pages(vma) > count - vma->vm_pgoff)
+		return -ENXIO;
+	return vm_map_pages(vma, sgt_handle(sgt)->pages, count);
+}
+
 void iommu_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
 		size_t size, enum dma_data_direction dir)
 {
diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 9668ddf3696e71..b7773201414c27 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -24,11 +24,6 @@ struct dma_map_ops {
 			gfp_t gfp);
 	void (*free_pages)(struct device *dev, size_t size, struct page *vaddr,
 			dma_addr_t dma_handle, enum dma_data_direction dir);
-	struct sg_table *(*alloc_noncontiguous)(struct device *dev, size_t size,
-			enum dma_data_direction dir, gfp_t gfp,
-			unsigned long attrs);
-	void (*free_noncontiguous)(struct device *dev, size_t size,
-			struct sg_table *sgt, enum dma_data_direction dir);
 	int (*mmap)(struct device *, struct vm_area_struct *,
 			void *, dma_addr_t, size_t, unsigned long attrs);
 
@@ -206,20 +201,6 @@ static inline int dma_mmap_from_global_coherent(struct vm_area_struct *vma,
 }
 #endif /* CONFIG_DMA_GLOBAL_POOL */
 
-/*
- * This is the actual return value from the ->alloc_noncontiguous method.
- * The users of the DMA API should only care about the sg_table, but to make
- * the DMA-API internal vmaping and freeing easier we stash away the page
- * array as well (except for the fallback case).  This can go away any time,
- * e.g. when a vmap-variant that takes a scatterlist comes along.
- */
-struct dma_sgt_handle {
-	struct sg_table sgt;
-	struct page **pages;
-};
-#define sgt_handle(sgt) \
-	container_of((sgt), struct dma_sgt_handle, sgt)
-
 int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
 		void *cpu_addr, dma_addr_t dma_addr, size_t size,
 		unsigned long attrs);
diff --git a/include/linux/iommu-dma.h b/include/linux/iommu-dma.h
index 1bb55ca1ab79d7..7bf145a52d6a1a 100644
--- a/include/linux/iommu-dma.h
+++ b/include/linux/iommu-dma.h
@@ -44,6 +44,12 @@ struct sg_table *iommu_dma_alloc_noncontiguous(struct device *dev, size_t size,
 		enum dma_data_direction dir, gfp_t gfp, unsigned long attrs);
 void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
 		struct sg_table *sgt, enum dma_data_direction dir);
+void *iommu_dma_vmap_noncontiguous(struct device *dev, size_t size,
+		struct sg_table *sgt);
+#define iommu_dma_vunmap_noncontiguous(dev, vaddr) \
+	vunmap(vaddr);
+int iommu_dma_mmap_noncontiguous(struct device *dev, struct vm_area_struct *vma,
+		size_t size, struct sg_table *sgt);
 void iommu_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
 		size_t size, enum dma_data_direction dir);
 void iommu_dma_sync_single_for_device(struct device *dev, dma_addr_t dma_handle,
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index b839683da0baf0..7911c754d9f42a 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -750,7 +750,6 @@ static struct sg_table *alloc_single_sgt(struct device *dev, size_t size,
 struct sg_table *dma_alloc_noncontiguous(struct device *dev, size_t size,
 		enum dma_data_direction dir, gfp_t gfp, unsigned long attrs)
 {
-	const struct dma_map_ops *ops = get_dma_ops(dev);
 	struct sg_table *sgt;
 
 	if (WARN_ON_ONCE(attrs & ~DMA_ATTR_ALLOC_SINGLE_PAGES))
@@ -758,9 +757,7 @@ struct sg_table *dma_alloc_noncontiguous(struct device *dev, size_t size,
 	if (WARN_ON_ONCE(gfp & __GFP_COMP))
 		return NULL;
 
-	if (ops && ops->alloc_noncontiguous)
-		sgt = ops->alloc_noncontiguous(dev, size, dir, gfp, attrs);
-	else if (use_dma_iommu(dev))
+	if (use_dma_iommu(dev))
 		sgt = iommu_dma_alloc_noncontiguous(dev, size, dir, gfp, attrs);
 	else
 		sgt = alloc_single_sgt(dev, size, dir, gfp);
@@ -786,13 +783,10 @@ static void free_single_sgt(struct device *dev, size_t size,
 void dma_free_noncontiguous(struct device *dev, size_t size,
 		struct sg_table *sgt, enum dma_data_direction dir)
 {
-	const struct dma_map_ops *ops = get_dma_ops(dev);
-
 	trace_dma_unmap_sg(dev, sgt->sgl, sgt->orig_nents, dir, 0);
 	debug_dma_unmap_sg(dev, sgt->sgl, sgt->orig_nents, dir);
-	if (ops && ops->free_noncontiguous)
-		ops->free_noncontiguous(dev, size, sgt, dir);
-	else if (use_dma_iommu(dev))
+
+	if (use_dma_iommu(dev))
 		iommu_dma_free_noncontiguous(dev, size, sgt, dir);
 	else
 		free_single_sgt(dev, size, sgt, dir);
@@ -802,37 +796,26 @@ EXPORT_SYMBOL_GPL(dma_free_noncontiguous);
 void *dma_vmap_noncontiguous(struct device *dev, size_t size,
 		struct sg_table *sgt)
 {
-	const struct dma_map_ops *ops = get_dma_ops(dev);
-	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 
-	if (ops && ops->alloc_noncontiguous)
-		return vmap(sgt_handle(sgt)->pages, count, VM_MAP, PAGE_KERNEL);
+	if (use_dma_iommu(dev))
+		return iommu_dma_vmap_noncontiguous(dev, size, sgt);
+
 	return page_address(sg_page(sgt->sgl));
 }
 EXPORT_SYMBOL_GPL(dma_vmap_noncontiguous);
 
 void dma_vunmap_noncontiguous(struct device *dev, void *vaddr)
 {
-	const struct dma_map_ops *ops = get_dma_ops(dev);
-
-	if (ops && ops->alloc_noncontiguous)
-		vunmap(vaddr);
+	if (use_dma_iommu(dev))
+		iommu_dma_vunmap_noncontiguous(dev, vaddr);
 }
 EXPORT_SYMBOL_GPL(dma_vunmap_noncontiguous);
 
 int dma_mmap_noncontiguous(struct device *dev, struct vm_area_struct *vma,
 		size_t size, struct sg_table *sgt)
 {
-	const struct dma_map_ops *ops = get_dma_ops(dev);
-
-	if (ops && ops->alloc_noncontiguous) {
-		unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
-
-		if (vma->vm_pgoff >= count ||
-		    vma_pages(vma) > count - vma->vm_pgoff)
-			return -ENXIO;
-		return vm_map_pages(vma, sgt_handle(sgt)->pages, count);
-	}
+	if (use_dma_iommu(dev))
+		return iommu_dma_mmap_noncontiguous(dev, vma, size, sgt);
 	return dma_mmap_pages(dev, vma, size, sg_page(sgt->sgl));
 }
 EXPORT_SYMBOL_GPL(dma_mmap_noncontiguous);