On Mon, Feb 19, 2018 at 4:07 PM, Anshuman Khandual <[email protected]> wrote: > 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. >
A nit below, in any case Reviewed-by: Andy Shevchenko <[email protected]> > 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; If it's ~2-3 characters over 80, I would rather still keep on the same line. > } > > /** > @@ -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 > -- With Best Regards, Andy Shevchenko
