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| author |   Anshuman Khandual <khandual@linux.vnet.ibm.com> | 2018-02-15 09:03:56 +0530 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2018-02-28 12:23:35 -0700 |
| commit | 723fbf563a6a9cefbd3c58e95694583ad1cb8704 (patch) | |
| tree | e7f7886eb7ee80e276e7efe6c56f95c36708240e /include/linux/scatterlist.h | |
| parent | Merge branch 'for-jens' of git://git.infradead.org/nvme into for-linus (diff) | |
| download | wireguard-linux-723fbf563a6a9cefbd3c58e95694583ad1cb8704.tar.xz wireguard-linux-723fbf563a6a9cefbd3c58e95694583ad1cb8704.zip | |
lib/scatterlist: Add SG_CHAIN and SG_END macros for LSB encodings
This replaces scatterlist->page_link LSB encodings with SG_CHAIN and
SG_END definitions without any functional change.
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include/linux/scatterlist.h')
| -rw-r--r-- | include/linux/scatterlist.h | 23 |
1 files changed, 13 insertions, 10 deletions
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 22b2131bcdcd..b6fe1815f5c4 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -65,16 +65,18 @@ struct sg_table { */ #define SG_MAGIC 0x87654321 +#define SG_CHAIN 0x01UL +#define SG_END 0x02UL /* * 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_END) #define sg_chain_ptr(sg) \ - ((struct scatterlist *) ((sg)->page_link & ~0x03)) + ((struct scatterlist *) ((sg)->page_link & ~(SG_CHAIN | SG_END))) /** * sg_assign_page - Assign a given page to an SG entry @@ -88,13 +90,13 @@ 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_CHAIN | SG_END); /* * 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_CHAIN | SG_END)); #ifdef CONFIG_DEBUG_SG BUG_ON(sg->sg_magic != SG_MAGIC); BUG_ON(sg_is_chain(sg)); @@ -130,7 +132,7 @@ 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_CHAIN | SG_END)); } /** @@ -178,7 +180,8 @@ 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_END; } /** @@ -198,8 +201,8 @@ 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_END; + sg->page_link &= ~SG_CHAIN; } /** @@ -215,7 +218,7 @@ 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_END; } /** |