Re: [PATCH 1/2] drivers: dma-coherent: Introduce interface for default DMA pool

[Robin Murphy]

On 20/07/17 11:19, Vladimir Murzin wrote:
> Christoph noticed [1] that default DMA pool in current form overload
> the DMA coherent infrastructure. In reply, Robin suggested [2] to
> split the per-device vs. global pool interfaces, so allocation/release
> from default DMA pool is driven by dma ops implementation.
> 
> This patch implements Robin's idea and provide interface to
> allocate/release/mmap the default (aka global) DMA pool.
> 
> To make it clear that existing *_from_coherent routines work on
> per-device pool rename them to *_from_dev_coherent.
> 
> [1] https://lkml.org/lkml/2017/7/7/370
> [2] https://lkml.org/lkml/2017/7/7/431
> 
> Cc: Vineet Gupta <vgupta@xxxxxxxxxxxx>
> Cc: Russell King <linux@xxxxxxxxxxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Will Deacon <will.deacon@xxxxxxx>
> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
> Suggested-by: Robin Murphy <robin.murphy@xxxxxxx>
> Tested-by: Andras Szemzo <sza@xxxxxx>
> Signed-off-by: Vladimir Murzin <vladimir.murzin@xxxxxxx>

I'd have left the factored-out static helpers named __*_from_coherent(),
as the _dev is not strictly true there, but it really doesn't matter as
far as I'm concerned:

Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>

Thanks for sorting it out.

Robin.

> ---
>  arch/arc/mm/dma.c           |   2 +-
>  arch/arm/mm/dma-mapping.c   |   2 +-
>  arch/arm64/mm/dma-mapping.c |   4 +-
>  arch/mips/mm/dma-default.c  |   2 +-
>  drivers/base/dma-coherent.c | 169 +++++++++++++++++++++++++++++---------------
>  drivers/base/dma-mapping.c  |   2 +-
>  include/linux/dma-mapping.h |  40 ++++++++---
>  7 files changed, 149 insertions(+), 72 deletions(-)
> 
> diff --git a/arch/arc/mm/dma.c b/arch/arc/mm/dma.c
> index 2a07e6e..71d3eff 100644
> --- a/arch/arc/mm/dma.c
> +++ b/arch/arc/mm/dma.c
> @@ -117,7 +117,7 @@ static int arc_dma_mmap(struct device *dev, struct vm_area_struct *vma,
>  
>  	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
>  
> -	if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
> +	if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
>  		return ret;
>  
>  	if (off < count && user_count <= (count - off)) {
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index e7380ba..fcf1473 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -851,7 +851,7 @@ static int __arm_dma_mmap(struct device *dev, struct vm_area_struct *vma,
>  	unsigned long pfn = dma_to_pfn(dev, dma_addr);
>  	unsigned long off = vma->vm_pgoff;
>  
> -	if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
> +	if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
>  		return ret;
>  
>  	if (off < nr_pages && nr_vma_pages <= (nr_pages - off)) {
> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> index e90cd1d..f27d4dd 100644
> --- a/arch/arm64/mm/dma-mapping.c
> +++ b/arch/arm64/mm/dma-mapping.c
> @@ -329,7 +329,7 @@ static int __swiotlb_mmap(struct device *dev,
>  	vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot,
>  					     is_device_dma_coherent(dev));
>  
> -	if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
> +	if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
>  		return ret;
>  
>  	return __swiotlb_mmap_pfn(vma, pfn, size);
> @@ -706,7 +706,7 @@ static int __iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
>  	vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot,
>  					     is_device_dma_coherent(dev));
>  
> -	if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
> +	if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
>  		return ret;
>  
>  	if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) {
> diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
> index e08598c..8e78251 100644
> --- a/arch/mips/mm/dma-default.c
> +++ b/arch/mips/mm/dma-default.c
> @@ -232,7 +232,7 @@ static int mips_dma_mmap(struct device *dev, struct vm_area_struct *vma,
>  	else
>  		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
>  
> -	if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
> +	if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
>  		return ret;
>  
>  	if (off < count && user_count <= (count - off)) {
> diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
> index 2ae24c2..d6f231c 100644
> --- a/drivers/base/dma-coherent.c
> +++ b/drivers/base/dma-coherent.c
> @@ -25,7 +25,7 @@ static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *de
>  {
>  	if (dev && dev->dma_mem)
>  		return dev->dma_mem;
> -	return dma_coherent_default_memory;
> +	return NULL;
>  }
>  
>  static inline dma_addr_t dma_get_device_base(struct device *dev,
> @@ -165,34 +165,15 @@ void *dma_mark_declared_memory_occupied(struct device *dev,
>  }
>  EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
>  
> -/**
> - * dma_alloc_from_coherent() - try to allocate memory from the per-device coherent area
> - *
> - * @dev:	device from which we allocate memory
> - * @size:	size of requested memory area
> - * @dma_handle:	This will be filled with the correct dma handle
> - * @ret:	This pointer will be filled with the virtual address
> - *		to allocated area.
> - *
> - * This function should be only called from per-arch dma_alloc_coherent()
> - * to support allocation from per-device coherent memory pools.
> - *
> - * Returns 0 if dma_alloc_coherent should continue with allocating from
> - * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
> - */
> -int dma_alloc_from_coherent(struct device *dev, ssize_t size,
> -				       dma_addr_t *dma_handle, void **ret)
> +static void *__dma_alloc_from_dev_coherent(struct dma_coherent_mem *mem,
> +				       ssize_t size, dma_addr_t *dma_handle)
>  {
> -	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
>  	int order = get_order(size);
>  	unsigned long flags;
>  	int pageno;
>  	int dma_memory_map;
> +	void *ret;
>  
> -	if (!mem)
> -		return 0;
> -
> -	*ret = NULL;
>  	spin_lock_irqsave(&mem->spinlock, flags);
>  
>  	if (unlikely(size > (mem->size << PAGE_SHIFT)))
> @@ -203,21 +184,51 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
>  		goto err;
>  
>  	/*
> -	 * Memory was found in the per-device area.
> +	 * Memory was found in the coherent area.
>  	 */
> -	*dma_handle = dma_get_device_base(dev, mem) + (pageno << PAGE_SHIFT);
> -	*ret = mem->virt_base + (pageno << PAGE_SHIFT);
> +	*dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
> +	ret = mem->virt_base + (pageno << PAGE_SHIFT);
>  	dma_memory_map = (mem->flags & DMA_MEMORY_MAP);
>  	spin_unlock_irqrestore(&mem->spinlock, flags);
>  	if (dma_memory_map)
> -		memset(*ret, 0, size);
> +		memset(ret, 0, size);
>  	else
> -		memset_io(*ret, 0, size);
> +		memset_io(ret, 0, size);
>  
> -	return 1;
> +	return ret;
>  
>  err:
>  	spin_unlock_irqrestore(&mem->spinlock, flags);
> +	return NULL;
> +}
> +
> +/**
> + * dma_alloc_from_dev_coherent() - try to allocate memory from the per-device coherent area
> + *
> + * @dev:	device from which we allocate memory
> + * @size:	size of requested memory area
> + * @dma_handle:	This will be filled with the correct dma handle
> + * @ret:	This pointer will be filled with the virtual address
> + *		to allocated area.
> + *
> + * This function should be only called from per-arch dma_alloc_coherent()
> + * to support allocation from per-device coherent memory pools.
> + *
> + * Returns 0 if dma_alloc_coherent should continue with allocating from
> + * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
> + */
> +int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size,
> +			    dma_addr_t *dma_handle, void **ret)
> +{
> +	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
> +
> +	if (!mem)
> +		return 0;
> +
> +	*ret = __dma_alloc_from_dev_coherent(mem, size, dma_handle);
> +	if (*ret)
> +		return 1;
> +
>  	/*
>  	 * In the case where the allocation can not be satisfied from the
>  	 * per-device area, try to fall back to generic memory if the
> @@ -225,25 +236,20 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
>  	 */
>  	return mem->flags & DMA_MEMORY_EXCLUSIVE;
>  }
> -EXPORT_SYMBOL(dma_alloc_from_coherent);
> +EXPORT_SYMBOL(dma_alloc_from_dev_coherent);
>  
> -/**
> - * dma_release_from_coherent() - try to free the memory allocated from per-device coherent memory pool
> - * @dev:	device from which the memory was allocated
> - * @order:	the order of pages allocated
> - * @vaddr:	virtual address of allocated pages
> - *
> - * This checks whether the memory was allocated from the per-device
> - * coherent memory pool and if so, releases that memory.
> - *
> - * Returns 1 if we correctly released the memory, or 0 if
> - * dma_release_coherent() should proceed with releasing memory from
> - * generic pools.
> - */
> -int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
> +void *dma_alloc_from_global_coherent(ssize_t size, dma_addr_t *dma_handle)
>  {
> -	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
> +	if (!dma_coherent_default_memory)
> +		return NULL;
>  
> +	return __dma_alloc_from_dev_coherent(dma_coherent_default_memory, size, dma_handle);
> +}
> +
> +
> +static int __dma_release_from_dev_coherent(struct dma_coherent_mem *mem,
> +				       int order, void *vaddr)
> +{
>  	if (mem && vaddr >= mem->virt_base && vaddr <
>  		   (mem->virt_base + (mem->size << PAGE_SHIFT))) {
>  		int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
> @@ -256,28 +262,42 @@ int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
>  	}
>  	return 0;
>  }
> -EXPORT_SYMBOL(dma_release_from_coherent);
>  
>  /**
> - * dma_mmap_from_coherent() - try to mmap the memory allocated from
> - * per-device coherent memory pool to userspace
> + * dma_release_from_dev_coherent() - try to free the memory allocated from per-device coherent memory pool
>   * @dev:	device from which the memory was allocated
> - * @vma:	vm_area for the userspace memory
> - * @vaddr:	cpu address returned by dma_alloc_from_coherent
> - * @size:	size of the memory buffer allocated by dma_alloc_from_coherent
> - * @ret:	result from remap_pfn_range()
> + * @order:	the order of pages allocated
> + * @vaddr:	virtual address of allocated pages
>   *
>   * This checks whether the memory was allocated from the per-device
> - * coherent memory pool and if so, maps that memory to the provided vma.
> + * coherent memory pool and if so, releases that memory.
>   *
> - * Returns 1 if we correctly mapped the memory, or 0 if the caller should
> - * proceed with mapping memory from generic pools.
> + * Returns 1 if we correctly released the memory, or 0 if
> + * dma_release_coherent() should proceed with releasing memory from
> + * generic pools.
>   */
> -int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma,
> -			   void *vaddr, size_t size, int *ret)
> +int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr)
>  {
>  	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
>  
> +	return __dma_release_from_dev_coherent(mem, order, vaddr);
> +}
> +EXPORT_SYMBOL(dma_release_from_dev_coherent);
> +
> +
> +int dma_release_from_global_coherent(int order, void *vaddr)
> +{
> +	if (!dma_coherent_default_memory)
> +		return 0;
> +
> +	return __dma_release_from_dev_coherent(dma_coherent_default_memory,
> +					   order, vaddr);
> +}
> +
> +static int __dma_mmap_from_dev_coherent(struct dma_coherent_mem *mem,
> +				    struct vm_area_struct *vma, void *vaddr,
> +				    size_t size, int *ret)
> +{
>  	if (mem && vaddr >= mem->virt_base && vaddr + size <=
>  		   (mem->virt_base + (mem->size << PAGE_SHIFT))) {
>  		unsigned long off = vma->vm_pgoff;
> @@ -296,7 +316,40 @@ int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma,
>  	}
>  	return 0;
>  }
> -EXPORT_SYMBOL(dma_mmap_from_coherent);
> +
> +/**
> + * dma_mmap_from_dev_coherent() - try to mmap the memory allocated from
> + * per-device coherent memory pool to userspace
> + * @dev:	device from which the memory was allocated
> + * @vma:	vm_area for the userspace memory
> + * @vaddr:	cpu address returned by dma_alloc_from_dev_coherent
> + * @size:	size of the memory buffer allocated by dma_alloc_from_dev_coherent
> + * @ret:	result from remap_pfn_range()
> + *
> + * This checks whether the memory was allocated from the per-device
> + * coherent memory pool and if so, maps that memory to the provided vma.
> + *
> + * Returns 1 if we correctly mapped the memory, or 0 if the caller should
> + * proceed with mapping memory from generic pools.
> + */
> +int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
> +			   void *vaddr, size_t size, int *ret)
> +{
> +	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
> +
> +	return __dma_mmap_from_dev_coherent(mem, vma, vaddr, size, ret);
> +}
> +EXPORT_SYMBOL(dma_mmap_from_dev_coherent);
> +
> +int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *vaddr,
> +				   size_t size, int *ret)
> +{
> +	if (!dma_coherent_default_memory)
> +		return 0;
> +
> +	return __dma_mmap_from_dev_coherent(dma_coherent_default_memory, vma,
> +					vaddr, size, ret);
> +}
>  
>  /*
>   * Support for reserved memory regions defined in device tree
> diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
> index 5096755..b555ff9 100644
> --- a/drivers/base/dma-mapping.c
> +++ b/drivers/base/dma-mapping.c
> @@ -235,7 +235,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
>  
>  	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
>  
> -	if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
> +	if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
>  		return ret;
>  
>  	if (off < count && user_count <= (count - off)) {
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index 843ab86..03c0196 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -157,16 +157,40 @@ static inline int is_device_dma_capable(struct device *dev)
>   * These three functions are only for dma allocator.
>   * Don't use them in device drivers.
>   */
> -int dma_alloc_from_coherent(struct device *dev, ssize_t size,
> +int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size,
>  				       dma_addr_t *dma_handle, void **ret);
> -int dma_release_from_coherent(struct device *dev, int order, void *vaddr);
> +int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr);
>  
> -int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma,
> +int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
>  			    void *cpu_addr, size_t size, int *ret);
> +
> +void *dma_alloc_from_global_coherent(ssize_t size, dma_addr_t *dma_handle);
> +int dma_release_from_global_coherent(int order, void *vaddr);
> +int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *cpu_addr,
> +				  size_t size, int *ret);
> +
>  #else
> -#define dma_alloc_from_coherent(dev, size, handle, ret) (0)
> -#define dma_release_from_coherent(dev, order, vaddr) (0)
> -#define dma_mmap_from_coherent(dev, vma, vaddr, order, ret) (0)
> +#define dma_alloc_from_dev_coherent(dev, size, handle, ret) (0)
> +#define dma_release_from_dev_coherent(dev, order, vaddr) (0)
> +#define dma_mmap_from_dev_coherent(dev, vma, vaddr, order, ret) (0)
> +
> +static inline void *dma_alloc_from_global_coherent(ssize_t size,
> +						   dma_addr_t *dma_handle)
> +{
> +	return NULL;
> +}
> +
> +static inline int dma_release_from_global_coherent(int order, void *vaddr)
> +{
> +	return 0;
> +}
> +
> +static inline int dma_mmap_from_global_coherent(struct vm_area_struct *vma,
> +						void *cpu_addr, size_t size,
> +						int *ret)
> +{
> +	return 0;
> +}
>  #endif /* CONFIG_HAVE_GENERIC_DMA_COHERENT */
>  
>  #ifdef CONFIG_HAS_DMA
> @@ -481,7 +505,7 @@ static inline void *dma_alloc_attrs(struct device *dev, size_t size,
>  
>  	BUG_ON(!ops);
>  
> -	if (dma_alloc_from_coherent(dev, size, dma_handle, &cpu_addr))
> +	if (dma_alloc_from_dev_coherent(dev, size, dma_handle, &cpu_addr))
>  		return cpu_addr;
>  
>  	if (!arch_dma_alloc_attrs(&dev, &flag))
> @@ -503,7 +527,7 @@ static inline void dma_free_attrs(struct device *dev, size_t size,
>  	BUG_ON(!ops);
>  	WARN_ON(irqs_disabled());
>  
> -	if (dma_release_from_coherent(dev, get_order(size), cpu_addr))
> +	if (dma_release_from_dev_coherent(dev, get_order(size), cpu_addr))
>  		return;
>  
>  	if (!ops->free || !cpu_addr)
>