On 02/13/2018 10:14 PM, Andy Shevchenko wrote: > On Sat, Feb 10, 2018 at 8:06 PM, Alexey Skidanov > <[email protected]> wrote: >> Currently, sg_page_count() may be used only inside the scatterlist.c file. >> >> However, the same calculation is done outside of scatterlist.c file >> causing to code duplication. >> >> To fix this, we move the sg_page_count() to the scatterlist.h file, making it >> accessible to other modules. > > Can you provide an example of potential (or existing?) use case? > This one, for example - drivers/staging/android/ion/ion_heap.c: for_each_sg(table->sgl, sg, table->nents, i) { int npages_this_entry = PAGE_ALIGN(sg->length) / PAGE_SIZE; struct page *page = sg_page(sg); BUG_ON(i >= npages); for (j = 0; j < npages_this_entry; j++) *(tmp++) = page++; }
One more is in the patch I have submitted for review. >> >> Signed-off-by: Alexey Skidanov <[email protected]> >> --- >> include/linux/scatterlist.h | 5 +++++ >> lib/scatterlist.c | 5 ----- >> 2 files changed, 5 insertions(+), 5 deletions(-) >> >> diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h >> index b7c8325..fe28148 100644 >> --- a/include/linux/scatterlist.h >> +++ b/include/linux/scatterlist.h >> @@ -248,6 +248,11 @@ static inline void *sg_virt(struct scatterlist *sg) >> return page_address(sg_page(sg)) + sg->offset; >> } >> >> +static inline int sg_page_count(struct scatterlist *sg) >> +{ >> + return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; >> +} >> + >> int sg_nents(struct scatterlist *sg); >> int sg_nents_for_len(struct scatterlist *sg, u64 len); >> struct scatterlist *sg_next(struct scatterlist *); >> diff --git a/lib/scatterlist.c b/lib/scatterlist.c >> index 7c1c55f..4a59131 100644 >> --- a/lib/scatterlist.c >> +++ b/lib/scatterlist.c >> @@ -486,11 +486,6 @@ void __sg_page_iter_start(struct sg_page_iter *piter, >> } >> EXPORT_SYMBOL(__sg_page_iter_start); >> >> -static int sg_page_count(struct scatterlist *sg) >> -{ >> - return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; >> -} >> - >> bool __sg_page_iter_next(struct sg_page_iter *piter) >> { >> if (!piter->__nents || !piter->sg) >> -- >> 2.7.4 >> > > >
