In crypto engine framework, one request can combine (copy) other requests'
scatterlists into its dynamic sg table to manage them together as a bulk
block , which can improve engine efficency with handling bulk block. Thus
we need some helper functions to manage dynamic scattertables.
This patch introduces 'sg_is_contiguous()' function to check if two
scatterlists are contiguous, 'sg_alloc_empty_table()' function to
allocate one empty dynamic sg table, 'sg_add_sg_to_table()' function
to copy one mapped scatterlist into sg table and 'sg_table_is_empty'
function to check if the sg table is empty.
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx>
---
include/linux/scatterlist.h | 33 +++++++++++++++++++++
lib/scatterlist.c | 69 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 102 insertions(+)
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 556ec1e..c1ed9f4 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -212,6 +212,20 @@ static inline void sg_unmark_end(struct scatterlist *sg)
}
/**
+ * sg_table_is_empty - Check if the sg table is empty
+ * @sgt: sg table
+ *
+ * Description:
+ * The 'orig_nents' member of one sg table is used to indicate how many
+ * scatterlists in the sg table.
+ *
+ **/
+static inline bool sg_table_is_empty(struct sg_table *sgt)
+{
+ return !sgt->orig_nents;
+}
+
+/**
* sg_phys - Return physical address of an sg entry
* @sg: SG entry
*
@@ -241,6 +255,23 @@ static inline void *sg_virt(struct scatterlist *sg)
return page_address(sg_page(sg)) + sg->offset;
}
+/**
+ * sg_is_contiguous - Check if the scatterlists are contiguous
+ * @sga: SG entry
+ * @sgb: SG entry
+ *
+ * Description:
+ * If the sga scatterlist is contiguous with the sgb scatterlist,
+ * that means they can be merged together.
+ *
+ **/
+static inline bool sg_is_contiguous(struct scatterlist *sga,
+ struct scatterlist *sgb)
+{
+ return *(unsigned long *)sg_virt(sga) + sga->length ==
+ *(unsigned long *)sg_virt(sgb);
+}
+
int sg_nents(struct scatterlist *sg);
int sg_nents_for_len(struct scatterlist *sg, u64 len);
struct scatterlist *sg_next(struct scatterlist *);
@@ -261,6 +292,8 @@ void sg_free_table(struct sg_table *);
int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int,
struct scatterlist *, gfp_t, sg_alloc_fn *);
int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
+int sg_alloc_empty_table(struct sg_table *, unsigned int, gfp_t);
+int sg_add_sg_to_table(struct sg_table *, struct scatterlist *);
int sg_alloc_table_from_pages(struct sg_table *sgt,
struct page **pages, unsigned int n_pages,
unsigned long offset, unsigned long size,
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 004fc70..6d3f3b0 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -370,6 +370,75 @@ int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
EXPORT_SYMBOL(sg_alloc_table);
/**
+ * sg_add_sg_to_table - Add one scatterlist into sg table
+ * @sgt: The sg table header to use
+ * @src: The sg need to be added into sg table
+ *
+ * Description:
+ * The 'nents' member indicates how many mapped scatterlists has been added
+ * in the dynamic sg table. The 'orig_nents' member indicates the size of the
+ * dynamic sg table.
+ *
+ * Copy one mapped @src@ scatterlist into the dynamic sg table and increase
+ * 'nents' member.
+ *
+ **/
+int sg_add_sg_to_table(struct sg_table *sgt, struct scatterlist *src)
+{
+ unsigned int i = 0, orig_nents = sgt->orig_nents;
+ struct scatterlist *sgl = sgt->sgl;
+ struct scatterlist *sg;
+
+ /* Check if there are enough space for the new sg to be added */
+ if (sgt->nents >= sgt->orig_nents)
+ return -EINVAL;
+
+ for_each_sg(sgl, sg, orig_nents, i) {
+ if (sgt->nents > 0 && i == (sgt->nents - 1)) {
+ sg_unmark_end(sg);
+ } else if (i == sgt->nents) {
+ memcpy(sg, src, sizeof(struct scatterlist));
+ sg_mark_end(sg);
+ sgt->nents++;
+ break;
+ }
+ }
+
+ return 0;
+}
+
+/**
+ * sg_alloc_empty_table - Allocate one empty dynamic sg table
+ * @sgt: The sg table header to use
+ * @nents: Number of entries in sg list
+ * @gfp_mask: GFP allocation mask
+ *
+ * Description:
+ * Allocate and initialize one dynamic sg table. One dynamic sg table means
+ * it need allocate @nents@ empty scatterlists entries and is used to copy
+ * other mapped scatterlists into the dynamic sg table.
+ *
+ * The 'nents' member indicates how many scatterlists has been copied into
+ * the dynamic sg table. It should set 0 which means there are no mapped
+ * scatterlists added in this sg table now.
+ *
+ * The 'orig_nents' member indicates the size of the dynamic sg table.
+ *
+ **/
+int sg_alloc_empty_table(struct sg_table *sgt, unsigned int nents,
+ gfp_t gfp_mask)
+{
+ int ret;
+
+ ret = sg_alloc_table(sgt, nents, gfp_mask);
+ if (ret)
+ return ret;
+
+ sgt->nents = 0;
+ return 0;
+}
+
+/**
* sg_alloc_table_from_pages - Allocate and initialize an sg table from
* an array of pages
* @sgt: The sg table header to use
--
1.7.9.5
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