Commit fea18777 authored by Petr Tesarik's avatar Petr Tesarik Committed by Christoph Hellwig
Browse files

swiotlb: add documentation and rename swiotlb_do_find_slots() 



Add some kernel-doc comments and move the existing documentation of struct
io_tlb_slot to its correct location. The latter was forgotten in commit
942a8186 ("swiotlb: move struct io_tlb_slot to swiotlb.c").

Use the opportunity to give swiotlb_do_find_slots() a more descriptive name
and make it clear how it differs from swiotlb_find_slots().

Signed-off-by: default avatarPetr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 05ee7741

include/linux/swiotlb.h

+11 −4
Original line number Diff line number Diff line
@@ -76,10 +76,6 @@ dma_addr_t swiotlb_map(struct device *dev, phys_addr_t phys, 
 * @nslabs:	The number of IO TLB blocks (in groups of 64) between @start and

 *		@end. For default swiotlb, this is command line adjustable via

 *		setup_io_tlb_npages.

 * @list:	The free list describing the number of free entries available

 *		from each index.

 * @orig_addr:	The original address corresponding to a mapped entry.

 * @alloc_size:	Size of the allocated buffer.

 * @debugfs:	The dentry to debugfs.

 * @late_alloc:	%true if allocated using the page allocator

 * @force_bounce: %true if swiotlb bouncing is forced
@@ -111,6 +107,17 @@ struct io_tlb_mem { 
#endif

};



/**

 * is_swiotlb_buffer() - check if a physical address belongs to a swiotlb

 * @dev:        Device which has mapped the buffer.

 * @paddr:      Physical address within the DMA buffer.

 *

 * Check if @paddr points into a bounce buffer.

 *

 * Return:

 * * %true if @paddr points into a bounce buffer

 * * %false otherwise

 */

static inline bool is_swiotlb_buffer(struct device *dev, phys_addr_t paddr)

{

	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;

kernel/dma/swiotlb.c

+55 −6
Original line number Diff line number Diff line
@@ -62,6 +62,13 @@ 


#define INVALID_PHYS_ADDR (~(phys_addr_t)0)



/**

 * struct io_tlb_slot - IO TLB slot descriptor

 * @orig_addr:	The original address corresponding to a mapped entry.

 * @alloc_size:	Size of the allocated buffer.

 * @list:	The free list describing the number of free entries available

 *		from each index.

 */

struct io_tlb_slot {

	phys_addr_t orig_addr;

	size_t alloc_size;
@@ -635,11 +642,22 @@ static void dec_used(struct io_tlb_mem *mem, unsigned int nslots) 
}

#endif /* CONFIG_DEBUG_FS */



/*

 * Find a suitable number of IO TLB entries size that will fit this request and

 * allocate a buffer from that IO TLB pool.

/**

 * swiotlb_area_find_slots() - search for slots in one IO TLB memory area

 * @dev:	Device which maps the buffer.

 * @area_index:	Index of the IO TLB memory area to be searched.

 * @orig_addr:	Original (non-bounced) IO buffer address.

 * @alloc_size: Total requested size of the bounce buffer,

 *		including initial alignment padding.

 * @alloc_align_mask:	Required alignment of the allocated buffer.

 *

 * Find a suitable sequence of IO TLB entries for the request and allocate

 * a buffer from the given IO TLB memory area.

 * This function takes care of locking.

 *

 * Return: Index of the first allocated slot, or -1 on error.

 */

static int swiotlb_do_find_slots(struct device *dev, int area_index,

static int swiotlb_area_find_slots(struct device *dev, int area_index,

		phys_addr_t orig_addr, size_t alloc_size,

		unsigned int alloc_align_mask)

{
@@ -734,6 +752,19 @@ static int swiotlb_do_find_slots(struct device *dev, int area_index, 
	return slot_index;

}



/**

 * swiotlb_find_slots() - search for slots in the whole swiotlb

 * @dev:	Device which maps the buffer.

 * @orig_addr:	Original (non-bounced) IO buffer address.

 * @alloc_size: Total requested size of the bounce buffer,

 *		including initial alignment padding.

 * @alloc_align_mask:	Required alignment of the allocated buffer.

 *

 * Search through the whole software IO TLB to find a sequence of slots that

 * match the allocation constraints.

 *

 * Return: Index of the first allocated slot, or -1 on error.

 */

static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,

		size_t alloc_size, unsigned int alloc_align_mask)

{
@@ -742,7 +773,7 @@ static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr, 
	int i = start, index;



	do {

		index = swiotlb_do_find_slots(dev, i, orig_addr, alloc_size,

		index = swiotlb_area_find_slots(dev, i, orig_addr, alloc_size,

						alloc_align_mask);

		if (index >= 0)

			return index;
@@ -755,6 +786,15 @@ static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr, 


#ifdef CONFIG_DEBUG_FS



/**

 * mem_used() - get number of used slots in an allocator

 * @mem:	Software IO TLB allocator.

 *

 * The result is accurate in this version of the function, because an atomic

 * counter is available if CONFIG_DEBUG_FS is set.

 *

 * Return: Number of used slots.

 */

static unsigned long mem_used(struct io_tlb_mem *mem)

{

	return atomic_long_read(&mem->total_used);
@@ -762,6 +802,15 @@ static unsigned long mem_used(struct io_tlb_mem *mem) 


#else /* !CONFIG_DEBUG_FS */



/**

 * mem_used() - get number of used slots in an allocator

 * @mem:	Software IO TLB allocator.

 *

 * The result is not accurate, because there is no locking of individual

 * areas.

 *

 * Return: Approximate number of used slots.

 */

static unsigned long mem_used(struct io_tlb_mem *mem)

{

	int i;