From 57a865f8088a544a3a25bb1a9b0072f5c42fa102 Mon Sep 17 00:00:00 2001 From: Hans Petter Selasky Date: Fri, 1 Jun 2018 12:09:07 +0000 Subject: [PATCH] Implement the __sg_alloc_table_from_pages() function based on the existing sg_alloc_table_from_pages() function in the LinuxKPI. This basically allow segments to have a limit, max_segment. Submitted by: Johannes Lundberg MFC after: 1 week Sponsored by: Mellanox Technologies Sponsored by: Limelight Networks --- .../common/include/linux/scatterlist.h | 35 +++++++++++++++---- 1 file changed, 29 insertions(+), 6 deletions(-) diff --git a/sys/compat/linuxkpi/common/include/linux/scatterlist.h b/sys/compat/linuxkpi/common/include/linux/scatterlist.h index 125b1acb7a33..5a19cd25b0b0 100644 --- a/sys/compat/linuxkpi/common/include/linux/scatterlist.h +++ b/sys/compat/linuxkpi/common/include/linux/scatterlist.h @@ -64,6 +64,8 @@ struct sg_page_iter { } internal; }; +#define SCATTERLIST_MAX_SEGMENT (-1U & ~(PAGE_SIZE - 1)) + #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) #define SG_MAGIC 0x87654321UL @@ -286,18 +288,26 @@ sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) } static inline int -sg_alloc_table_from_pages(struct sg_table *sgt, +__sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages, unsigned int count, unsigned long off, unsigned long size, - gfp_t gfp_mask) + unsigned int max_segment, gfp_t gfp_mask) { - unsigned int i, segs, cur; + unsigned int i, segs, cur, len; int rc; struct scatterlist *s; + if (__predict_false(!max_segment || offset_in_page(max_segment))) + return (-EINVAL); + + len = 0; for (segs = i = 1; i < count; ++i) { - if (page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1) + len += PAGE_SIZE; + if (len >= max_segment || + page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1) { ++segs; + len = 0; + } } if (__predict_false((rc = sg_alloc_table(sgt, segs, gfp_mask)))) return (rc); @@ -307,10 +317,13 @@ sg_alloc_table_from_pages(struct sg_table *sgt, unsigned long seg_size; unsigned int j; - for (j = cur + 1; j < count; ++j) - if (page_to_pfn(pages[j]) != + len = 0; + for (j = cur + 1; j < count; ++j) { + len += PAGE_SIZE; + if (len >= max_segment || page_to_pfn(pages[j]) != page_to_pfn(pages[j - 1]) + 1) break; + } seg_size = ((j - cur) << PAGE_SHIFT) - off; sg_set_page(s, pages[cur], min(size, seg_size), off); @@ -321,6 +334,16 @@ sg_alloc_table_from_pages(struct sg_table *sgt, return (0); } +static inline int +sg_alloc_table_from_pages(struct sg_table *sgt, + struct page **pages, unsigned int count, + unsigned long off, unsigned long size, + gfp_t gfp_mask) +{ + + return (__sg_alloc_table_from_pages(sgt, pages, count, off, size, + SCATTERLIST_MAX_SEGMENT, gfp_mask)); +} static inline int sg_nents(struct scatterlist *sg)