SG: Move functions to lib/scatterlist.c and add sg chaining allocator helpers (0db9299f) · Commits · e / devices / android_kernel_fairphone_FP4

include/linux/scatterlist.h

+25 −100

Original line number	Diff line number	Diff line
		@@ -7,6 +7,12 @@
		#include <linux/string.h>
		#include <asm/io.h>

		struct sg_table {
		struct scatterlist sgl; / the list */
		unsigned int nents; /* number of mapped entries */
		unsigned int orig_nents; /* original size of list */
		};

		/*
		* Notes on SG table design.
		*
		@@ -106,71 +112,12 @@ static inline void sg_set_buf(struct scatterlist sg, const void buf,
		sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
		}

		/**
		* sg_next - return the next scatterlist entry in a list
		* @sg: The current sg entry
		*
		* Description:
		* Usually the next entry will be @sg@ + 1, but if this sg element is part
		* of a chained scatterlist, it could jump to the start of a new
		* scatterlist array.
		*
		**/
		static inline struct scatterlist sg_next(struct scatterlist sg)
		{
		#ifdef CONFIG_DEBUG_SG
		BUG_ON(sg->sg_magic != SG_MAGIC);
		#endif
		if (sg_is_last(sg))
		return NULL;

		sg++;
		if (unlikely(sg_is_chain(sg)))
		sg = sg_chain_ptr(sg);

		return sg;
		}

		/*
		* Loop over each sg element, following the pointer to a new list if necessary
		*/
		#define for_each_sg(sglist, sg, nr, __i) \
		for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))

		/**
		* sg_last - return the last scatterlist entry in a list
		* @sgl: First entry in the scatterlist
		* @nents: Number of entries in the scatterlist
		*
		* Description:
		* Should only be used casually, it (currently) scan the entire list
		* to get the last entry.
		*
		* Note that the @sgl@ pointer passed in need not be the first one,
		* the important bit is that @nents@ denotes the number of entries that
		* exist from @sgl@.
		*
		**/
		static inline struct scatterlist sg_last(struct scatterlist sgl,
		unsigned int nents)
		{
		#ifndef ARCH_HAS_SG_CHAIN
		struct scatterlist *ret = &sgl[nents - 1];
		#else
		struct scatterlist sg, ret = NULL;
		unsigned int i;

		for_each_sg(sgl, sg, nents, i)
		ret = sg;

		#endif
		#ifdef CONFIG_DEBUG_SG
		BUG_ON(sgl[0].sg_magic != SG_MAGIC);
		BUG_ON(!sg_is_last(ret));
		#endif
		return ret;
		}

		/**
		* sg_chain - Chain two sglists together
		* @prv: First scatterlist
		@@ -222,47 +169,6 @@ static inline void sg_mark_end(struct scatterlist *sg)
		sg->page_link &= ~0x01;
		}

		/**
		* sg_init_table - Initialize SG table
		* @sgl: The SG table
		* @nents: Number of entries in table
		*
		* Notes:
		* If this is part of a chained sg table, sg_mark_end() should be
		* used only on the last table part.
		*
		**/
		static inline void sg_init_table(struct scatterlist *sgl, unsigned int nents)
		{
		memset(sgl, 0, sizeof(sgl) nents);
		#ifdef CONFIG_DEBUG_SG
		{
		unsigned int i;
		for (i = 0; i < nents; i++)
		sgl[i].sg_magic = SG_MAGIC;
		}
		#endif
		sg_mark_end(&sgl[nents - 1]);
		}

		/**
		* sg_init_one - Initialize a single entry sg list
		* @sg: SG entry
		* @buf: Virtual address for IO
		* @buflen: IO length
		*
		* Notes:
		* This should not be used on a single entry that is part of a larger
		* table. Use sg_init_table() for that.
		*
		**/
		static inline void sg_init_one(struct scatterlist sg, const void buf,
		unsigned int buflen)
		{
		sg_init_table(sg, 1);
		sg_set_buf(sg, buf, buflen);
		}

		/**
		* sg_phys - Return physical address of an sg entry
		* @sg: SG entry
		@@ -293,4 +199,23 @@ static inline void sg_virt(struct scatterlist sg)
		return page_address(sg_page(sg)) + sg->offset;
		}

		struct scatterlist sg_next(struct scatterlist );
		struct scatterlist sg_last(struct scatterlist s, unsigned int);
		void sg_init_table(struct scatterlist *, unsigned int);
		void sg_init_one(struct scatterlist , const void , unsigned int);

		typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t);
		typedef void (sg_free_fn)(struct scatterlist *, unsigned int);

		void __sg_free_table(struct sg_table , sg_free_fn );
		void sg_free_table(struct sg_table *);
		int __sg_alloc_table(struct sg_table , unsigned int, gfp_t, sg_alloc_fn );
		int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);

		/*
		* Maximum number of entries that will be allocated in one piece, if
		* a list larger than this is required then chaining will be utilized.
		*/
		#define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))

		#endif /* _LINUX_SCATTERLIST_H */

lib/Makefile

+1 −1

Original line number	Diff line number	Diff line
		@@ -6,7 +6,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
		rbtree.o radix-tree.o dump_stack.o \
		idr.o int_sqrt.o extable.o prio_tree.o \
		sha1.o irq_regs.o reciprocal_div.o argv_split.o \
		proportions.o prio_heap.o
		proportions.o prio_heap.o scatterlist.o

		lib-$(CONFIG_MMU) += ioremap.o
		lib-$(CONFIG_SMP) += cpumask.o

lib/scatterlist.c

0 → 100644

+281 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com>
		*
		* Scatterlist handling helpers.
		*
		* This source code is licensed under the GNU General Public License,
		* Version 2. See the file COPYING for more details.
		*/
		#include <linux/module.h>
		#include <linux/scatterlist.h>

		/**
		* sg_next - return the next scatterlist entry in a list
		* @sg: The current sg entry
		*
		* Description:
		* Usually the next entry will be @sg@ + 1, but if this sg element is part
		* of a chained scatterlist, it could jump to the start of a new
		* scatterlist array.
		*
		**/
		struct scatterlist sg_next(struct scatterlist sg)
		{
		#ifdef CONFIG_DEBUG_SG
		BUG_ON(sg->sg_magic != SG_MAGIC);
		#endif
		if (sg_is_last(sg))
		return NULL;

		sg++;
		if (unlikely(sg_is_chain(sg)))
		sg = sg_chain_ptr(sg);

		return sg;
		}
		EXPORT_SYMBOL(sg_next);

		/**
		* sg_last - return the last scatterlist entry in a list
		* @sgl: First entry in the scatterlist
		* @nents: Number of entries in the scatterlist
		*
		* Description:
		* Should only be used casually, it (currently) scans the entire list
		* to get the last entry.
		*
		* Note that the @sgl@ pointer passed in need not be the first one,
		* the important bit is that @nents@ denotes the number of entries that
		* exist from @sgl@.
		*
		**/
		struct scatterlist sg_last(struct scatterlist sgl, unsigned int nents)
		{
		#ifndef ARCH_HAS_SG_CHAIN
		struct scatterlist *ret = &sgl[nents - 1];
		#else
		struct scatterlist sg, ret = NULL;
		unsigned int i;

		for_each_sg(sgl, sg, nents, i)
		ret = sg;

		#endif
		#ifdef CONFIG_DEBUG_SG
		BUG_ON(sgl[0].sg_magic != SG_MAGIC);
		BUG_ON(!sg_is_last(ret));
		#endif
		return ret;
		}
		EXPORT_SYMBOL(sg_last);

		/**
		* sg_init_table - Initialize SG table
		* @sgl: The SG table
		* @nents: Number of entries in table
		*
		* Notes:
		* If this is part of a chained sg table, sg_mark_end() should be
		* used only on the last table part.
		*
		**/
		void sg_init_table(struct scatterlist *sgl, unsigned int nents)
		{
		memset(sgl, 0, sizeof(sgl) nents);
		#ifdef CONFIG_DEBUG_SG
		{
		unsigned int i;
		for (i = 0; i < nents; i++)
		sgl[i].sg_magic = SG_MAGIC;
		}
		#endif
		sg_mark_end(&sgl[nents - 1]);
		}
		EXPORT_SYMBOL(sg_init_table);

		/**
		* sg_init_one - Initialize a single entry sg list
		* @sg: SG entry
		* @buf: Virtual address for IO
		* @buflen: IO length
		*
		**/
		void sg_init_one(struct scatterlist sg, const void buf, unsigned int buflen)
		{
		sg_init_table(sg, 1);
		sg_set_buf(sg, buf, buflen);
		}
		EXPORT_SYMBOL(sg_init_one);

		/*
		* The default behaviour of sg_alloc_table() is to use these kmalloc/kfree
		* helpers.
		*/
		static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
		{
		if (nents == SG_MAX_SINGLE_ALLOC)
		return (struct scatterlist *) __get_free_page(gfp_mask);
		else
		return kmalloc(nents * sizeof(struct scatterlist), gfp_mask);
		}

		static void sg_kfree(struct scatterlist *sg, unsigned int nents)
		{
		if (nents == SG_MAX_SINGLE_ALLOC)
		free_page((unsigned long) sg);
		else
		kfree(sg);
		}

		/**
		* __sg_free_table - Free a previously mapped sg table
		* @table: The sg table header to use
		* @free_fn: Free function
		*
		* Description:
		* Free an sg table previously allocated and setup with __sg_alloc_table().
		*
		**/
		void __sg_free_table(struct sg_table table, sg_free_fn free_fn)
		{
		struct scatterlist sgl, next;

		if (unlikely(!table->sgl))
		return;

		sgl = table->sgl;
		while (table->orig_nents) {
		unsigned int alloc_size = table->orig_nents;
		unsigned int sg_size;

		/*
		* If we have more than SG_MAX_SINGLE_ALLOC segments left,
		* then assign 'next' to the sg table after the current one.
		* sg_size is then one less than alloc size, since the last
		* element is the chain pointer.
		*/
		if (alloc_size > SG_MAX_SINGLE_ALLOC) {
		next = sg_chain_ptr(&sgl[SG_MAX_SINGLE_ALLOC - 1]);
		alloc_size = SG_MAX_SINGLE_ALLOC;
		sg_size = alloc_size - 1;
		} else {
		sg_size = alloc_size;
		next = NULL;
		}

		table->orig_nents -= sg_size;
		free_fn(sgl, alloc_size);
		sgl = next;
		}

		table->sgl = NULL;
		}
		EXPORT_SYMBOL(__sg_free_table);

		/**
		* sg_free_table - Free a previously allocated sg table
		* @table: The mapped sg table header
		*
		**/
		void sg_free_table(struct sg_table *table)
		{
		__sg_free_table(table, sg_kfree);
		}
		EXPORT_SYMBOL(sg_free_table);

		/**
		* __sg_alloc_table - Allocate and initialize an sg table with given allocator
		* @table: The sg table header to use
		* @nents: Number of entries in sg list
		* @gfp_mask: GFP allocation mask
		* @alloc_fn: Allocator to use
		*
		* Notes:
		* If this function returns non-0 (eg failure), the caller must call
		* __sg_free_table() to cleanup any leftover allocations.
		*
		**/
		int __sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask,
		sg_alloc_fn *alloc_fn)
		{
		struct scatterlist sg, prv;
		unsigned int left;

		#ifndef ARCH_HAS_SG_CHAIN
		BUG_ON(nents > SG_MAX_SINGLE_ALLOC);
		#endif

		memset(table, 0, sizeof(*table));

		left = nents;
		prv = NULL;
		do {
		unsigned int sg_size, alloc_size = left;

		if (alloc_size > SG_MAX_SINGLE_ALLOC) {
		alloc_size = SG_MAX_SINGLE_ALLOC;
		sg_size = alloc_size - 1;
		} else
		sg_size = alloc_size;

		left -= sg_size;

		sg = alloc_fn(alloc_size, gfp_mask);
		if (unlikely(!sg))
		return -ENOMEM;

		sg_init_table(sg, alloc_size);
		table->nents = table->orig_nents += sg_size;

		/*
		* If this is the first mapping, assign the sg table header.
		* If this is not the first mapping, chain previous part.
		*/
		if (prv)
		sg_chain(prv, SG_MAX_SINGLE_ALLOC, sg);
		else
		table->sgl = sg;

		/*
		* If no more entries after this one, mark the end
		*/
		if (!left)
		sg_mark_end(&sg[sg_size - 1]);

		/*
		* only really needed for mempool backed sg allocations (like
		* SCSI), a possible improvement here would be to pass the
		* table pointer into the allocator and let that clear these
		* flags
		*/
		gfp_mask &= ~__GFP_WAIT;
		gfp_mask \|= __GFP_HIGH;
		prv = sg;
		} while (left);

		return 0;
		}
		EXPORT_SYMBOL(__sg_alloc_table);

		/**
		* sg_alloc_table - Allocate and initialize an sg table
		* @table: The sg table header to use
		* @nents: Number of entries in sg list
		* @gfp_mask: GFP allocation mask
		*
		* Description:
		* Allocate and initialize an sg table. If @nents@ is larger than
		* SG_MAX_SINGLE_ALLOC a chained sg table will be setup.
		*
		**/
		int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
		{
		int ret;

		ret = __sg_alloc_table(table, nents, gfp_mask, sg_kmalloc);
		if (unlikely(ret))
		__sg_free_table(table, sg_kfree);

		return ret;
		}
		EXPORT_SYMBOL(sg_alloc_table);