From 18dabf473e15850c0dbc8ff13ac1e2806d542c15 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 22 Oct 2007 19:57:20 +0200 Subject: [PATCH] Change table chaining layout Change the page member of the scatterlist structure to be an unsigned long, and encode more stuff in the lower bits: - Bits 0 and 1 zero: this is a normal sg entry. Next sg entry is located at sg + 1. - Bit 0 set: this is a chain entry, the next real entry is at ->page_link with the two low bits masked off. - Bit 1 set: this is the final entry in the sg entry. sg_next() will return NULL when passed such an entry. It's thus important that sg table users use the proper accessors to get and set the page member. Signed-off-by: Jens Axboe --- include/asm-alpha/scatterlist.h | 2 +- include/asm-arm/scatterlist.h | 2 +- include/asm-avr32/scatterlist.h | 2 +- include/asm-blackfin/scatterlist.h | 2 +- include/asm-cris/scatterlist.h | 2 +- include/asm-frv/scatterlist.h | 2 +- include/asm-h8300/scatterlist.h | 2 +- include/asm-ia64/scatterlist.h | 2 +- include/asm-m32r/scatterlist.h | 2 +- include/asm-m68k/scatterlist.h | 2 +- include/asm-m68knommu/scatterlist.h | 2 +- include/asm-mips/scatterlist.h | 2 +- include/asm-parisc/scatterlist.h | 2 +- include/asm-powerpc/scatterlist.h | 2 +- include/asm-s390/scatterlist.h | 2 +- include/asm-sh/scatterlist.h | 2 +- include/asm-sh64/scatterlist.h | 2 +- include/asm-sparc/scatterlist.h | 2 +- include/asm-sparc64/scatterlist.h | 2 +- include/asm-v850/scatterlist.h | 2 +- include/asm-x86/dma-mapping_32.h | 4 +- include/asm-x86/scatterlist_32.h | 2 +- include/asm-x86/scatterlist_64.h | 2 +- include/asm-xtensa/scatterlist.h | 2 +- include/linux/scatterlist.h | 78 ++++++++++++++++++++--------- 25 files changed, 79 insertions(+), 49 deletions(-) diff --git a/include/asm-alpha/scatterlist.h b/include/asm-alpha/scatterlist.h index 917365405e8..b7647063bd5 100644 --- a/include/asm-alpha/scatterlist.h +++ b/include/asm-alpha/scatterlist.h @@ -5,7 +5,7 @@ #include struct scatterlist { - struct page *page; + unsigned long page_link; unsigned int offset; unsigned int length; diff --git a/include/asm-arm/scatterlist.h b/include/asm-arm/scatterlist.h index de2f65eb42e..ab1d85dd023 100644 --- a/include/asm-arm/scatterlist.h +++ b/include/asm-arm/scatterlist.h @@ -5,7 +5,7 @@ #include struct scatterlist { - struct page *page; /* buffer page */ + unsigned long page_link; unsigned int offset; /* buffer offset */ dma_addr_t dma_address; /* dma address */ unsigned int length; /* length */ diff --git a/include/asm-avr32/scatterlist.h b/include/asm-avr32/scatterlist.h index c6d5ce3b3a2..1356f29d89f 100644 --- a/include/asm-avr32/scatterlist.h +++ b/include/asm-avr32/scatterlist.h @@ -4,7 +4,7 @@ #include struct scatterlist { - struct page *page; + unsigned long page_link; unsigned int offset; dma_addr_t dma_address; unsigned int length; diff --git a/include/asm-blackfin/scatterlist.h b/include/asm-blackfin/scatterlist.h index 60e07b92044..384af549e5b 100644 --- a/include/asm-blackfin/scatterlist.h +++ b/include/asm-blackfin/scatterlist.h @@ -4,7 +4,7 @@ #include struct scatterlist { - struct page *page; + unsigned long page_link; unsigned int offset; dma_addr_t dma_address; unsigned int length; diff --git a/include/asm-cris/scatterlist.h b/include/asm-cris/scatterlist.h index 4bdc44c4ac3..5a8a83440d3 100644 --- a/include/asm-cris/scatterlist.h +++ b/include/asm-cris/scatterlist.h @@ -6,7 +6,7 @@ struct scatterlist { unsigned int length; /* The following is i386 highmem junk - not used by us */ - struct page * page; /* Location for highmem page, if any */ + unsigned long page_link; unsigned int offset;/* for highmem, page offset */ }; diff --git a/include/asm-frv/scatterlist.h b/include/asm-frv/scatterlist.h index 8e827fa853f..53dade7b2e1 100644 --- a/include/asm-frv/scatterlist.h +++ b/include/asm-frv/scatterlist.h @@ -22,7 +22,7 @@ * and that's it. There's no excuse for not highmem enabling YOUR driver. /jens */ struct scatterlist { - struct page *page; /* Location for highmem page, if any */ + unsigned long page_link; unsigned int offset; /* for highmem, page offset */ dma_addr_t dma_address; diff --git a/include/asm-h8300/scatterlist.h b/include/asm-h8300/scatterlist.h index 985fdf54eac..7e41983d6b2 100644 --- a/include/asm-h8300/scatterlist.h +++ b/include/asm-h8300/scatterlist.h @@ -4,7 +4,7 @@ #include struct scatterlist { - struct page *page; + unsigned long page_link; unsigned int offset; dma_addr_t dma_address; unsigned int length; diff --git a/include/asm-ia64/scatterlist.h b/include/asm-ia64/scatterlist.h index 7d5234d5031..2f76ce30496 100644 --- a/include/asm-ia64/scatterlist.h +++ b/include/asm-ia64/scatterlist.h @@ -9,7 +9,7 @@ #include struct scatterlist { - struct page *page; + unsigned long page_link; unsigned int offset; unsigned int length; /* buffer length */ diff --git a/include/asm-m32r/scatterlist.h b/include/asm-m32r/scatterlist.h index 352415ff5eb..33b4b4d2c89 100644 --- a/include/asm-m32r/scatterlist.h +++ b/include/asm-m32r/scatterlist.h @@ -6,7 +6,7 @@ struct scatterlist { char * address; /* Location data is to be transferred to, NULL for * highmem page */ - struct page * page; /* Location for highmem page, if any */ + unsigned long page_link; unsigned int offset;/* for highmem, page offset */ dma_addr_t dma_address; diff --git a/include/asm-m68k/scatterlist.h b/include/asm-m68k/scatterlist.h index 24887a2d9c7..e06bb891048 100644 --- a/include/asm-m68k/scatterlist.h +++ b/include/asm-m68k/scatterlist.h @@ -4,7 +4,7 @@ #include struct scatterlist { - struct page *page; + unsigned long page_link; unsigned int offset; unsigned int length; diff --git a/include/asm-m68knommu/scatterlist.h b/include/asm-m68knommu/scatterlist.h index 4da79d3d3f3..28bed41dc80 100644 --- a/include/asm-m68knommu/scatterlist.h +++ b/include/asm-m68knommu/scatterlist.h @@ -5,7 +5,7 @@ #include struct scatterlist { - struct page *page; + unsigned long page_link; unsigned int offset; dma_addr_t dma_address; unsigned int length; diff --git a/include/asm-mips/scatterlist.h b/include/asm-mips/scatterlist.h index 7af104c95b2..787797cdb0a 100644 --- a/include/asm-mips/scatterlist.h +++ b/include/asm-mips/scatterlist.h @@ -4,7 +4,7 @@ #include struct scatterlist { - struct page * page; + unsigned long page_link; unsigned int offset; dma_addr_t dma_address; unsigned int length; diff --git a/include/asm-parisc/scatterlist.h b/include/asm-parisc/scatterlist.h index e7211c74844..26da9146fff 100644 --- a/include/asm-parisc/scatterlist.h +++ b/include/asm-parisc/scatterlist.h @@ -5,7 +5,7 @@ #include struct scatterlist { - struct page *page; + unsigned long page_link; unsigned int offset; unsigned int length; diff --git a/include/asm-powerpc/scatterlist.h b/include/asm-powerpc/scatterlist.h index b075f619c3b..b9f1dbc2484 100644 --- a/include/asm-powerpc/scatterlist.h +++ b/include/asm-powerpc/scatterlist.h @@ -14,7 +14,7 @@ #include struct scatterlist { - struct page *page; + unsigned long page_link; unsigned int offset; unsigned int length; diff --git a/include/asm-s390/scatterlist.h b/include/asm-s390/scatterlist.h index a43b3afc5e2..eb3948690d6 100644 --- a/include/asm-s390/scatterlist.h +++ b/include/asm-s390/scatterlist.h @@ -2,7 +2,7 @@ #define _ASMS390_SCATTERLIST_H struct scatterlist { - struct page *page; + unsigned long page_link; unsigned int offset; unsigned int length; }; diff --git a/include/asm-sh/scatterlist.h b/include/asm-sh/scatterlist.h index b9ae53c3836..bc7c809e16f 100644 --- a/include/asm-sh/scatterlist.h +++ b/include/asm-sh/scatterlist.h @@ -4,7 +4,7 @@ #include struct scatterlist { - struct page * page; /* Location for highmem page, if any */ + unsigned long page_link; unsigned int offset;/* for highmem, page offset */ dma_addr_t dma_address; unsigned int length; diff --git a/include/asm-sh64/scatterlist.h b/include/asm-sh64/scatterlist.h index 1c723f2d7a9..0afd856e218 100644 --- a/include/asm-sh64/scatterlist.h +++ b/include/asm-sh64/scatterlist.h @@ -14,7 +14,7 @@ #include struct scatterlist { - struct page * page; /* Location for highmem page, if any */ + unsigned long page_link; unsigned int offset;/* for highmem, page offset */ dma_addr_t dma_address; unsigned int length; diff --git a/include/asm-sparc/scatterlist.h b/include/asm-sparc/scatterlist.h index 4055af90ad7..45b16f1072b 100644 --- a/include/asm-sparc/scatterlist.h +++ b/include/asm-sparc/scatterlist.h @@ -5,7 +5,7 @@ #include struct scatterlist { - struct page *page; + unsigned long page_link; unsigned int offset; unsigned int length; diff --git a/include/asm-sparc64/scatterlist.h b/include/asm-sparc64/scatterlist.h index 703c5bbe6c8..4cbaf7c6b0b 100644 --- a/include/asm-sparc64/scatterlist.h +++ b/include/asm-sparc64/scatterlist.h @@ -6,7 +6,7 @@ #include struct scatterlist { - struct page *page; + unsigned long page_link; unsigned int offset; unsigned int length; diff --git a/include/asm-v850/scatterlist.h b/include/asm-v850/scatterlist.h index 56f402920db..db91febc210 100644 --- a/include/asm-v850/scatterlist.h +++ b/include/asm-v850/scatterlist.h @@ -17,7 +17,7 @@ #include struct scatterlist { - struct page *page; + unsigned long page_link; unsigned offset; dma_addr_t dma_address; unsigned length; diff --git a/include/asm-x86/dma-mapping_32.h b/include/asm-x86/dma-mapping_32.h index 6a2d26cb5da..55f01bd9e55 100644 --- a/include/asm-x86/dma-mapping_32.h +++ b/include/asm-x86/dma-mapping_32.h @@ -45,9 +45,9 @@ dma_map_sg(struct device *dev, struct scatterlist *sglist, int nents, WARN_ON(nents == 0 || sglist[0].length == 0); for_each_sg(sglist, sg, nents, i) { - BUG_ON(!sg->page); + BUG_ON(!sg_page(sg)); - sg->dma_address = page_to_phys(sg->page) + sg->offset; + sg->dma_address = sg_phys(sg); } flush_write_buffers(); diff --git a/include/asm-x86/scatterlist_32.h b/include/asm-x86/scatterlist_32.h index bd5164aa8f6..140a5b37fa7 100644 --- a/include/asm-x86/scatterlist_32.h +++ b/include/asm-x86/scatterlist_32.h @@ -4,7 +4,7 @@ #include struct scatterlist { - struct page *page; + unsigned long page_link; unsigned int offset; dma_addr_t dma_address; unsigned int length; diff --git a/include/asm-x86/scatterlist_64.h b/include/asm-x86/scatterlist_64.h index ef3986ba4b7..e3447846e03 100644 --- a/include/asm-x86/scatterlist_64.h +++ b/include/asm-x86/scatterlist_64.h @@ -4,7 +4,7 @@ #include struct scatterlist { - struct page *page; + unsigned long page_link; unsigned int offset; unsigned int length; dma_addr_t dma_address; diff --git a/include/asm-xtensa/scatterlist.h b/include/asm-xtensa/scatterlist.h index ca337a29429..3b8aba5d2c6 100644 --- a/include/asm-xtensa/scatterlist.h +++ b/include/asm-xtensa/scatterlist.h @@ -14,7 +14,7 @@ #include struct scatterlist { - struct page *page; + unsigned long page_link; unsigned int offset; dma_addr_t dma_address; unsigned int length; diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 1645795cbb1..c6136e8a7f5 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -2,9 +2,26 @@ #define _LINUX_SCATTERLIST_H #include -#include #include #include +#include + +/* + * Notes on SG table design. + * + * Architectures must provide an unsigned long page_link field in the + * scatterlist struct. We use that to place the page pointer AND encode + * information about the sg table as well. The two lower bits are reserved + * for this information. + * + * If bit 0 is set, then the page_link contains a pointer to the next sg + * table list. Otherwise the next entry is at sg + 1. + * + * If bit 1 is set, then this sg entry is the last element in a list. + * + * See sg_next(). + * + */ /** * sg_set_page - Set sg entry to point at given page @@ -20,11 +37,20 @@ **/ static inline void sg_set_page(struct scatterlist *sg, struct page *page) { - sg->page = page; + unsigned long page_link = sg->page_link & 0x3; + + sg->page_link = page_link | (unsigned long) page; } -#define sg_page(sg) ((sg)->page) +#define sg_page(sg) ((struct page *) ((sg)->page_link & ~0x3)) +/** + * sg_set_buf - Set sg entry to point at given data + * @sg: SG entry + * @buf: Data + * @buflen: Data length + * + **/ static inline void sg_set_buf(struct scatterlist *sg, const void *buf, unsigned int buflen) { @@ -38,26 +64,27 @@ static inline void sg_set_buf(struct scatterlist *sg, const void *buf, * 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_is_chain(sg) ((sg)->page_link & 0x01) +#define sg_is_last(sg) ((sg)->page_link & 0x02) #define sg_chain_ptr(sg) \ - ((struct scatterlist *) ((unsigned long) (sg)->page & ~0x01)) + ((struct scatterlist *) ((sg)->page_link & ~0x03)) /** * 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. + * 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) { - sg++; + if (sg_is_last(sg)) + return NULL; + sg++; if (unlikely(sg_is_chain(sg))) sg = sg_chain_ptr(sg); @@ -75,14 +102,15 @@ static inline struct scatterlist *sg_next(struct scatterlist *sg) * @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. + * 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@. + * 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) { @@ -105,16 +133,17 @@ static inline struct scatterlist *sg_last(struct scatterlist *sgl, * @prv_nents: Number of entries in prv * @sgl: Second scatterlist * - * Links @prv@ and @sgl@ together, to form a longer scatterlist. + * Description: + * 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); + prv[prv_nents - 1].page_link = (unsigned long) sgl | 0x01; } /** @@ -128,13 +157,14 @@ static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents, **/ static inline void sg_mark_end(struct scatterlist *sgl, unsigned int nents) { + sgl[nents - 1].page_link = 0x02; } static inline void __sg_mark_end(struct scatterlist *sg) { + sg->page_link |= 0x02; } - /** * sg_init_one - Initialize a single entry sg list * @sg: SG entry @@ -187,7 +217,7 @@ static inline unsigned long sg_phys(struct scatterlist *sg) /** * sg_virt - Return virtual address of an sg entry - * @sg: SG entry + * @sg: SG entry * * Description: * This calls page_address() on the page in this sg entry, and adds the -- 2.20.1