Commit 68fbda7d authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'sg' of git://git.kernel.dk/linux-2.6-block 

* 'sg' of git://git.kernel.dk/linux-2.6-block:
  SG: work with the SCSI fixed maximum allocations.
  SG: Convert SCSI to use scatterlist helpers for sg chaining
  SG: Move functions to lib/scatterlist.c and add sg chaining allocator helpers
parents d4928196 7cedb1f1

drivers/scsi/scsi_lib.c

+22 −118
Original line number Diff line number Diff line
@@ -739,138 +739,43 @@ static inline unsigned int scsi_sgtable_index(unsigned short nents) 
	return index;

}



struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)

static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents)

{

	struct scsi_host_sg_pool *sgp;

	struct scatterlist *sgl, *prev, *ret;

	unsigned int index;

	int this, left;



	BUG_ON(!cmd->use_sg);



	left = cmd->use_sg;

	ret = prev = NULL;

	do {

		this = left;

		if (this > SCSI_MAX_SG_SEGMENTS) {

			this = SCSI_MAX_SG_SEGMENTS - 1;

			index = SG_MEMPOOL_NR - 1;

		} else

			index = scsi_sgtable_index(this);



		left -= this;



		sgp = scsi_sg_pools + index;



		sgl = mempool_alloc(sgp->pool, gfp_mask);

		if (unlikely(!sgl))

			goto enomem;



		sg_init_table(sgl, sgp->size);



		/*

		 * first loop through, set initial index and return value

		 */

		if (!ret)

			ret = sgl;



		/*

		 * chain previous sglist, if any. we know the previous

		 * sglist must be the biggest one, or we would not have

		 * ended up doing another loop.

		 */

		if (prev)

			sg_chain(prev, SCSI_MAX_SG_SEGMENTS, sgl);



		/*

		 * if we have nothing left, mark the last segment as

		 * end-of-list

		 */

		if (!left)

			sg_mark_end(&sgl[this - 1]);



		/*

		 * don't allow subsequent mempool allocs to sleep, it would

		 * violate the mempool principle.

		 */

		gfp_mask &= ~__GFP_WAIT;

		gfp_mask |= __GFP_HIGH;

		prev = sgl;

	} while (left);



	/*

	 * ->use_sg may get modified after dma mapping has potentially

	 * shrunk the number of segments, so keep a copy of it for free.

	 */

	cmd->__use_sg = cmd->use_sg;

	return ret;

enomem:

	if (ret) {

		/*

		 * Free entries chained off ret. Since we were trying to

		 * allocate another sglist, we know that all entries are of

		 * the max size.

		 */

		sgp = scsi_sg_pools + SG_MEMPOOL_NR - 1;

		prev = ret;

		ret = &ret[SCSI_MAX_SG_SEGMENTS - 1];



		while ((sgl = sg_chain_ptr(ret)) != NULL) {

			ret = &sgl[SCSI_MAX_SG_SEGMENTS - 1];

	sgp = scsi_sg_pools + scsi_sgtable_index(nents);

	mempool_free(sgl, sgp->pool);

}



		mempool_free(prev, sgp->pool);

	}

	return NULL;

}



EXPORT_SYMBOL(scsi_alloc_sgtable);



void scsi_free_sgtable(struct scsi_cmnd *cmd)

static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)

{

	struct scatterlist *sgl = cmd->request_buffer;

	struct scsi_host_sg_pool *sgp;



	/*

	 * if this is the biggest size sglist, check if we have

	 * chained parts we need to free

	 */

	if (cmd->__use_sg > SCSI_MAX_SG_SEGMENTS) {

		unsigned short this, left;

		struct scatterlist *next;

		unsigned int index;



		left = cmd->__use_sg - (SCSI_MAX_SG_SEGMENTS - 1);

		next = sg_chain_ptr(&sgl[SCSI_MAX_SG_SEGMENTS - 1]);

		while (left && next) {

			sgl = next;

			this = left;

			if (this > SCSI_MAX_SG_SEGMENTS) {

				this = SCSI_MAX_SG_SEGMENTS - 1;

				index = SG_MEMPOOL_NR - 1;

			} else

				index = scsi_sgtable_index(this);

	sgp = scsi_sg_pools + scsi_sgtable_index(nents);

	return mempool_alloc(sgp->pool, gfp_mask);

}



			left -= this;

int scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)

{

	int ret;



			sgp = scsi_sg_pools + index;

	BUG_ON(!cmd->use_sg);



			if (left)

				next = sg_chain_ptr(&sgl[sgp->size - 1]);

	ret = __sg_alloc_table(&cmd->sg_table, cmd->use_sg,

			       SCSI_MAX_SG_SEGMENTS, gfp_mask, scsi_sg_alloc);

	if (unlikely(ret))

		__sg_free_table(&cmd->sg_table, SCSI_MAX_SG_SEGMENTS,

				scsi_sg_free);



			mempool_free(sgl, sgp->pool);

	cmd->request_buffer = cmd->sg_table.sgl;

	return ret;

}



		/*

		 * Restore original, will be freed below

		 */

		sgl = cmd->request_buffer;

		sgp = scsi_sg_pools + SG_MEMPOOL_NR - 1;

	} else

		sgp = scsi_sg_pools + scsi_sgtable_index(cmd->__use_sg);

EXPORT_SYMBOL(scsi_alloc_sgtable);



	mempool_free(sgl, sgp->pool);

void scsi_free_sgtable(struct scsi_cmnd *cmd)

{

	__sg_free_table(&cmd->sg_table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);

}



EXPORT_SYMBOL(scsi_free_sgtable);
@@ -1120,8 +1025,7 @@ static int scsi_init_io(struct scsi_cmnd *cmd) 
	/*

	 * If sg table allocation fails, requeue request later.

	 */

	cmd->request_buffer = scsi_alloc_sgtable(cmd, GFP_ATOMIC);

	if (unlikely(!cmd->request_buffer)) {

	if (unlikely(scsi_alloc_sgtable(cmd, GFP_ATOMIC))) {

		scsi_unprep_request(req);

		return BLKPREP_DEFER;

	}

drivers/scsi/scsi_tgt_lib.c

+1 −2
Original line number Diff line number Diff line
@@ -359,8 +359,7 @@ static int scsi_tgt_init_cmd(struct scsi_cmnd *cmd, gfp_t gfp_mask) 
	int count;



	cmd->use_sg = rq->nr_phys_segments;

	cmd->request_buffer = scsi_alloc_sgtable(cmd, gfp_mask);

	if (!cmd->request_buffer)

	if (scsi_alloc_sgtable(cmd, gfp_mask))

		return -ENOMEM;



	cmd->request_bufflen = rq->data_len;

include/linux/scatterlist.h

+26 −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 +199,24 @@ 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 *, unsigned int, sg_free_fn *);

void sg_free_table(struct sg_table *);

int __sg_alloc_table(struct sg_table *, unsigned int, 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 */

include/scsi/scsi_cmnd.h

+3 −4
Original line number Diff line number Diff line
@@ -8,7 +8,6 @@ 
#include <linux/scatterlist.h>



struct request;

struct scatterlist;

struct Scsi_Host;

struct scsi_device;
@@ -68,8 +67,8 @@ struct scsi_cmnd { 
	void *request_buffer;		/* Actual requested buffer */



	/* These elements define the operation we ultimately want to perform */

	struct sg_table sg_table;

	unsigned short use_sg;	/* Number of pieces of scatter-gather */

	unsigned short __use_sg;



	unsigned underflow;	/* Return error if less than

				   this amount is transferred */
@@ -128,14 +127,14 @@ extern void *scsi_kmap_atomic_sg(struct scatterlist *sg, int sg_count, 
				 size_t *offset, size_t *len);

extern void scsi_kunmap_atomic_sg(void *virt);



extern struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *, gfp_t);

extern int scsi_alloc_sgtable(struct scsi_cmnd *, gfp_t);

extern void scsi_free_sgtable(struct scsi_cmnd *);



extern int scsi_dma_map(struct scsi_cmnd *cmd);

extern void scsi_dma_unmap(struct scsi_cmnd *cmd);



#define scsi_sg_count(cmd) ((cmd)->use_sg)

#define scsi_sglist(cmd) ((struct scatterlist *)(cmd)->request_buffer)

#define scsi_sglist(cmd) ((cmd)->sg_table.sgl)

#define scsi_bufflen(cmd) ((cmd)->request_bufflen)



static inline void scsi_set_resid(struct scsi_cmnd *cmd, int resid)

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