From 96b418c960af0d5c7185ff5c4af9376eb37ac9d3 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 9 May 2007 09:02:57 +0200 Subject: Add sg helpers for iterating over a scatterlist table First step to being able to change the scatterlist setup without having to modify drivers (a lot :-) Signed-off-by: Jens Axboe --- include/linux/scatterlist.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include/linux') diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 4efbd9c445f5..bed5ab4d756a 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -20,4 +20,13 @@ static inline void sg_init_one(struct scatterlist *sg, const void *buf, sg_set_buf(sg, buf, buflen); } +#define sg_next(sg) ((sg) + 1) +#define sg_last(sg, nents) (&(sg[(nents) - 1])) + +/* + * 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)) + #endif /* _LINUX_SCATTERLIST_H */ -- cgit v1.2.2 From 70eb8040dc81212c884a464b75e37dca8014f3ad Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 16 Jul 2007 21:17:16 +0200 Subject: Add chained sg support to linux/scatterlist.h The core of the patch - allow the last sg element in a scatterlist table to point to the start of a new table. We overload the LSB of the page pointer to indicate whether this is a valid sg entry, or merely a link to the next list. Includes a fix from Bartlomiej Zolnierkiewicz correcting the ifdef ARCH_HAS_SG_CHAIN guarding sg_last(). Signed-off-by: Jens Axboe --- include/linux/scatterlist.h | 79 +++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 77 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index bed5ab4d756a..2dc7464cce52 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -20,8 +20,36 @@ static inline void sg_init_one(struct scatterlist *sg, const void *buf, sg_set_buf(sg, buf, buflen); } -#define sg_next(sg) ((sg) + 1) -#define sg_last(sg, nents) (&(sg[(nents) - 1])) +/* + * We overload the LSB of the page pointer to indicate whether it's + * a valid sg entry, or whether it points to the start of a new scatterlist. + * Those low bits are there for everyone! (thanks mason :-) + */ +#define sg_is_chain(sg) ((unsigned long) (sg)->page & 0x01) +#define sg_chain_ptr(sg) \ + ((struct scatterlist *) ((unsigned long) (sg)->page & ~0x01)) + +/** + * sg_next - return the next scatterlist entry in a list + * @sg: The current sg entry + * + * 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. + * + * Note that the caller must ensure that there are further entries after + * the current entry, this function will NOT return NULL for an end-of-list. + * + */ +static inline struct scatterlist *sg_next(struct scatterlist *sg) +{ + 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 @@ -29,4 +57,51 @@ static inline void sg_init_one(struct scatterlist *sg, const void *buf, #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 + * + * 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; + int i; + + for_each_sg(sgl, sg, nents, i) + ret = sg; + +#endif + return ret; +} + +/** + * sg_chain - Chain two sglists together + * @prv: First scatterlist + * @prv_nents: Number of entries in prv + * @sgl: Second scatterlist + * + * Links @prv@ and @sgl@ together, to form a longer scatterlist. + * + */ +static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents, + struct scatterlist *sgl) +{ +#ifndef ARCH_HAS_SG_CHAIN + BUG(); +#endif + prv[prv_nents - 1].page = (struct page *) ((unsigned long) sgl | 0x01); +} + #endif /* _LINUX_SCATTERLIST_H */ -- cgit v1.2.2 From 8726021626780a73e795c9b939e1ee49ac8c9136 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 16 Oct 2007 11:14:12 +0200 Subject: libata: convert to using sg helpers This converts libata to using the sg helpers for looking up sg elements, instead of doing it manually. Signed-off-by: Jens Axboe --- include/linux/libata.h | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) (limited to 'include/linux') diff --git a/include/linux/libata.h b/include/linux/libata.h index 229a9ff9f924..377e6d4d9be3 100644 --- a/include/linux/libata.h +++ b/include/linux/libata.h @@ -29,7 +29,7 @@ #include #include #include -#include +#include #include #include #include @@ -416,6 +416,7 @@ struct ata_queued_cmd { unsigned long flags; /* ATA_QCFLAG_xxx */ unsigned int tag; unsigned int n_elem; + unsigned int n_iter; unsigned int orig_n_elem; int dma_dir; @@ -426,7 +427,7 @@ struct ata_queued_cmd { unsigned int nbytes; unsigned int curbytes; - unsigned int cursg; + struct scatterlist *cursg; unsigned int cursg_ofs; struct scatterlist sgent; @@ -1043,7 +1044,7 @@ ata_sg_is_last(struct scatterlist *sg, struct ata_queued_cmd *qc) return 1; if (qc->pad_len) return 0; - if (((sg - qc->__sg) + 1) == qc->n_elem) + if (qc->n_iter == qc->n_elem) return 1; return 0; } @@ -1051,6 +1052,7 @@ ata_sg_is_last(struct scatterlist *sg, struct ata_queued_cmd *qc) static inline struct scatterlist * ata_qc_first_sg(struct ata_queued_cmd *qc) { + qc->n_iter = 0; if (qc->n_elem) return qc->__sg; if (qc->pad_len) @@ -1063,8 +1065,8 @@ ata_qc_next_sg(struct scatterlist *sg, struct ata_queued_cmd *qc) { if (sg == &qc->pad_sgent) return NULL; - if (++sg - qc->__sg < qc->n_elem) - return sg; + if (++qc->n_iter < qc->n_elem) + return sg_next(sg); if (qc->pad_len) return &qc->pad_sgent; return NULL; @@ -1309,9 +1311,11 @@ static inline void ata_qc_reinit(struct ata_queued_cmd *qc) qc->dma_dir = DMA_NONE; qc->__sg = NULL; qc->flags = 0; - qc->cursg = qc->cursg_ofs = 0; + qc->cursg = NULL; + qc->cursg_ofs = 0; qc->nbytes = qc->curbytes = 0; qc->n_elem = 0; + qc->n_iter = 0; qc->err_mask = 0; qc->pad_len = 0; qc->sect_size = ATA_SECT_SIZE; -- cgit v1.2.2 From ba2da2f8d61a9d2e24754c6311a4ab6a5e70060a Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 24 Jul 2007 14:42:11 +0200 Subject: i2o: sg chaining support Acked-by: Alan Cox Signed-off-by: Jens Axboe --- include/linux/i2o.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/i2o.h b/include/linux/i2o.h index 9752307d16ba..7da5b98d90e6 100644 --- a/include/linux/i2o.h +++ b/include/linux/i2o.h @@ -32,6 +32,7 @@ #include /* work_struct */ #include #include +#include #include #include /* Needed for MUTEX init macros */ @@ -837,7 +838,7 @@ static inline int i2o_dma_map_sg(struct i2o_controller *c, if ((sizeof(dma_addr_t) > 4) && c->pae_support) *mptr++ = cpu_to_le32(i2o_dma_high(sg_dma_address(sg))); #endif - sg++; + sg = sg_next(sg); } *sg_ptr = mptr; -- cgit v1.2.2 From 55c16a70041ba55e235c5944dccb9c1de0dd3ca6 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 25 Jul 2007 08:13:56 +0200 Subject: IDE: sg chaining support Acked-by: Bartlomiej Zolnierkiewicz Signed-off-by: Jens Axboe --- include/linux/ide.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/ide.h b/include/linux/ide.h index 234fa3df24f6..30a1931466a6 100644 --- a/include/linux/ide.h +++ b/include/linux/ide.h @@ -772,7 +772,7 @@ typedef struct hwif_s { unsigned int nsect; unsigned int nleft; - unsigned int cursg; + struct scatterlist *cursg; unsigned int cursg_ofs; int rqsize; /* max sectors per request */ -- cgit v1.2.2