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authorTvrtko Ursulin <tvrtko.ursulin@intel.com>2017-08-03 12:13:51 +0300
committerTvrtko Ursulin <tvrtko.ursulin@intel.com>2017-09-07 12:48:29 +0300
commit89d8589cd72c6f48b19c370517d16f3ee23909df (patch)
tree6b00e8b0121a55b72dc9098a412395cf99692575 /lib/scatterlist.c
parentc125906b839b794c580a5de911de65bd2c63aaee (diff)
downloadlinux-89d8589cd72c6f48b19c370517d16f3ee23909df.tar.xz
lib/scatterlist: Introduce and export __sg_alloc_table_from_pages
Drivers like i915 benefit from being able to control the maxium size of the sg coalesced segment while building the scatter- gather list. Introduce and export the __sg_alloc_table_from_pages function which will allow it that control. v2: Reorder parameters. (Chris Wilson) v3: Fix incomplete reordering in v2. v4: max_segment needs to be page aligned. v5: Rebase. v6: Rebase. v7: Fix spelling in commit and mention max segment size in __sg_alloc_table_from_pages kerneldoc. (Andrew Morton) Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: linux-kernel@vger.kernel.org Cc: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Link: https://patchwork.freedesktop.org/patch/msgid/20170803091351.23594-1-tvrtko.ursulin@linux.intel.com
Diffstat (limited to 'lib/scatterlist.c')
-rw-r--r--lib/scatterlist.c66
1 files changed, 49 insertions, 17 deletions
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 7b2e74da2c44..7c1c55f7daaa 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -370,35 +370,38 @@ int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
EXPORT_SYMBOL(sg_alloc_table);
/**
- * sg_alloc_table_from_pages - Allocate and initialize an sg table from
- * an array of pages
- * @sgt: The sg table header to use
- * @pages: Pointer to an array of page pointers
- * @n_pages: Number of pages in the pages array
- * @offset: Offset from start of the first page to the start of a buffer
- * @size: Number of valid bytes in the buffer (after offset)
- * @gfp_mask: GFP allocation mask
+ * __sg_alloc_table_from_pages - Allocate and initialize an sg table from
+ * an array of pages
+ * @sgt: The sg table header to use
+ * @pages: Pointer to an array of page pointers
+ * @n_pages: Number of pages in the pages array
+ * @offset: Offset from start of the first page to the start of a buffer
+ * @size: Number of valid bytes in the buffer (after offset)
+ * @max_segment: Maximum size of a scatterlist node in bytes (page aligned)
+ * @gfp_mask: GFP allocation mask
*
* Description:
* Allocate and initialize an sg table from a list of pages. Contiguous
- * ranges of the pages are squashed into a single scatterlist node. A user
- * may provide an offset at a start and a size of valid data in a buffer
- * specified by the page array. The returned sg table is released by
- * sg_free_table.
+ * ranges of the pages are squashed into a single scatterlist node up to the
+ * maximum size specified in @max_segment. An user may provide an offset at a
+ * start and a size of valid data in a buffer specified by the page array.
+ * The returned sg table is released by sg_free_table.
*
* Returns:
* 0 on success, negative error on failure
*/
-int sg_alloc_table_from_pages(struct sg_table *sgt,
- struct page **pages, unsigned int n_pages,
- unsigned int offset, unsigned long size,
- gfp_t gfp_mask)
+int __sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
+ unsigned int n_pages, unsigned int offset,
+ unsigned long size, unsigned int max_segment,
+ gfp_t gfp_mask)
{
- const unsigned int max_segment = SCATTERLIST_MAX_SEGMENT;
unsigned int chunks, cur_page, seg_len, i;
int ret;
struct scatterlist *s;
+ if (WARN_ON(!max_segment || offset_in_page(max_segment)))
+ return -EINVAL;
+
/* compute number of contiguous chunks */
chunks = 1;
seg_len = 0;
@@ -440,6 +443,35 @@ int sg_alloc_table_from_pages(struct sg_table *sgt,
return 0;
}
+EXPORT_SYMBOL(__sg_alloc_table_from_pages);
+
+/**
+ * sg_alloc_table_from_pages - Allocate and initialize an sg table from
+ * an array of pages
+ * @sgt: The sg table header to use
+ * @pages: Pointer to an array of page pointers
+ * @n_pages: Number of pages in the pages array
+ * @offset: Offset from start of the first page to the start of a buffer
+ * @size: Number of valid bytes in the buffer (after offset)
+ * @gfp_mask: GFP allocation mask
+ *
+ * Description:
+ * Allocate and initialize an sg table from a list of pages. Contiguous
+ * ranges of the pages are squashed into a single scatterlist node. A user
+ * may provide an offset at a start and a size of valid data in a buffer
+ * specified by the page array. The returned sg table is released by
+ * sg_free_table.
+ *
+ * Returns:
+ * 0 on success, negative error on failure
+ */
+int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
+ unsigned int n_pages, unsigned int offset,
+ unsigned long size, gfp_t gfp_mask)
+{
+ return __sg_alloc_table_from_pages(sgt, pages, n_pages, offset, size,
+ SCATTERLIST_MAX_SEGMENT, gfp_mask);
+}
EXPORT_SYMBOL(sg_alloc_table_from_pages);
void __sg_page_iter_start(struct sg_page_iter *piter,