This replaces scatterlist->page_link LSB encodings with SG_CHAIN and SG_LAST definitions without any functional change. While here also add macro definitions SG_PAGE_BITS and SG_PAGE_MASK.
Signed-off-by: Anshuman Khandual <[email protected]> --- Changes in V3: - Changed SG_END as SG_LAST due to a build failure - Added SG_PAGE_BITS and SG_PAGE_MASK as per Tvrtko - Used BIT() macro as per Chris Changes in V2: - Changed SG_EMARK as SG_END as per Johannes and Tvrtko - Added 'UL' to the constants as per Bart include/linux/scatterlist.h | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 22b2131bcdcd..494b84c7f3c8 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -66,15 +66,20 @@ struct sg_table { #define SG_MAGIC 0x87654321 +#define SG_CHAIN BIT(0) +#define SG_LAST BIT(1) +#define SG_PAGE_BITS (SG_CHAIN | SG_LAST) +#define SG_PAGE_MASK (~SG_PAGE_BITS) + /* * 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) ((sg)->page_link & 0x01) -#define sg_is_last(sg) ((sg)->page_link & 0x02) +#define sg_is_chain(sg) ((sg)->page_link & SG_CHAIN) +#define sg_is_last(sg) ((sg)->page_link & SG_LAST) #define sg_chain_ptr(sg) \ - ((struct scatterlist *) ((sg)->page_link & ~0x03)) + ((struct scatterlist *) ((sg)->page_link & SG_PAGE_MASK)) /** * sg_assign_page - Assign a given page to an SG entry @@ -88,13 +93,13 @@ struct sg_table { **/ static inline void sg_assign_page(struct scatterlist *sg, struct page *page) { - unsigned long page_link = sg->page_link & 0x3; + unsigned long page_link = sg->page_link & SG_PAGE_BITS; /* * In order for the low bit stealing approach to work, pages * must be aligned at a 32-bit boundary as a minimum. */ - BUG_ON((unsigned long) page & 0x03); + BUG_ON((unsigned long) page & SG_PAGE_BITS); #ifdef CONFIG_DEBUG_SG BUG_ON(sg->sg_magic != SG_MAGIC); BUG_ON(sg_is_chain(sg)); @@ -130,7 +135,7 @@ static inline struct page *sg_page(struct scatterlist *sg) BUG_ON(sg->sg_magic != SG_MAGIC); BUG_ON(sg_is_chain(sg)); #endif - return (struct page *)((sg)->page_link & ~0x3); + return (struct page *)((sg)->page_link & SG_PAGE_MASK); } /** @@ -178,7 +183,8 @@ static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents, * Set lowest bit to indicate a link pointer, and make sure to clear * the termination bit if it happens to be set. */ - prv[prv_nents - 1].page_link = ((unsigned long) sgl | 0x01) & ~0x02; + prv[prv_nents - 1].page_link = ((unsigned long) sgl | SG_CHAIN) + & ~SG_LAST; } /** @@ -198,8 +204,8 @@ static inline void sg_mark_end(struct scatterlist *sg) /* * Set termination bit, clear potential chain bit */ - sg->page_link |= 0x02; - sg->page_link &= ~0x01; + sg->page_link |= SG_LAST; + sg->page_link &= ~SG_CHAIN; } /** @@ -215,7 +221,7 @@ static inline void sg_unmark_end(struct scatterlist *sg) #ifdef CONFIG_DEBUG_SG BUG_ON(sg->sg_magic != SG_MAGIC); #endif - sg->page_link &= ~0x02; + sg->page_link &= ~SG_LAST; } /** -- 2.11.0
