@@ -403,6 +403,7 @@ __i915_gem_userptr_alloc_pages(struct drm_i915_gem_object *obj,
unsigned int max_segment = i915_sg_segment_size();
struct sg_table *st;
unsigned int sg_page_sizes;
+ struct scatterlist *sg;
int ret;
st = kmalloc(sizeof(*st), GFP_KERNEL);
@@ -410,13 +411,12 @@ __i915_gem_userptr_alloc_pages(struct drm_i915_gem_object *obj,
return ERR_PTR(-ENOMEM);
alloc_table:
- ret = __sg_alloc_table_from_pages(st, pvec, num_pages,
- 0, num_pages << PAGE_SHIFT,
- max_segment,
- GFP_KERNEL);
- if (ret) {
+ sg = __sg_alloc_table_from_pages(st, pvec, num_pages, 0,
+ num_pages << PAGE_SHIFT, max_segment,
+ NULL, 0, GFP_KERNEL);
+ if (IS_ERR(sg)) {
kfree(st);
- return ERR_PTR(ret);
+ return ERR_CAST(sg);
}
ret = i915_gem_gtt_prepare_pages(obj, st);
@@ -419,6 +419,7 @@ static int vmw_ttm_map_dma(struct vmw_ttm_tt *vmw_tt)
int ret = 0;
static size_t sgl_size;
static size_t sgt_size;
+ struct scatterlist *sg;
if (vmw_tt->mapped)
return 0;
@@ -441,13 +442,15 @@ static int vmw_ttm_map_dma(struct vmw_ttm_tt *vmw_tt)
if (unlikely(ret != 0))
return ret;
- ret = __sg_alloc_table_from_pages
- (&vmw_tt->sgt, vsgt->pages, vsgt->num_pages, 0,
- (unsigned long) vsgt->num_pages << PAGE_SHIFT,
- dma_get_max_seg_size(dev_priv->dev->dev),
- GFP_KERNEL);
- if (unlikely(ret != 0))
+ sg = __sg_alloc_table_from_pages(&vmw_tt->sgt, vsgt->pages,
+ vsgt->num_pages, 0,
+ (unsigned long) vsgt->num_pages << PAGE_SHIFT,
+ dma_get_max_seg_size(dev_priv->dev->dev),
+ NULL, 0, GFP_KERNEL);
+ if (IS_ERR(sg)) {
+ ret = PTR_ERR(sg);
goto out_sg_alloc_fail;
+ }
if (vsgt->num_pages > vmw_tt->sgt.nents) {
uint64_t over_alloc =
@@ -165,6 +165,22 @@ static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
#define for_each_sgtable_dma_sg(sgt, sg, i) \
for_each_sg((sgt)->sgl, sg, (sgt)->nents, i)
+static inline void __sg_chain(struct scatterlist *chain_sg,
+ struct scatterlist *sgl)
+{
+ /*
+ * offset and length are unused for chain entry. Clear them.
+ */
+ chain_sg->offset = 0;
+ chain_sg->length = 0;
+
+ /*
+ * Set lowest bit to indicate a link pointer, and make sure to clear
+ * the termination bit if it happens to be set.
+ */
+ chain_sg->page_link = ((unsigned long) sgl | SG_CHAIN) & ~SG_END;
+}
+
/**
* sg_chain - Chain two sglists together
* @prv: First scatterlist
@@ -178,18 +194,7 @@ static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
struct scatterlist *sgl)
{
- /*
- * offset and length are unused for chain entry. Clear them.
- */
- prv[prv_nents - 1].offset = 0;
- prv[prv_nents - 1].length = 0;
-
- /*
- * 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 | SG_CHAIN)
- & ~SG_END;
+ __sg_chain(&prv[prv_nents - 1], sgl);
}
/**
@@ -286,10 +291,11 @@ void sg_free_table(struct sg_table *);
int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int,
struct scatterlist *, unsigned int, gfp_t, sg_alloc_fn *);
int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
-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);
+struct scatterlist *__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,
+ struct scatterlist *prv, unsigned int left_pages,
+ 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, gfp_t gfp_mask);
@@ -365,6 +365,37 @@ int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
}
EXPORT_SYMBOL(sg_alloc_table);
+static struct scatterlist *get_next_sg(struct sg_table *table,
+ struct scatterlist *cur,
+ unsigned long needed_sges,
+ gfp_t gfp_mask)
+{
+ struct scatterlist *new_sg, *next_sg;
+ unsigned int alloc_size;
+
+ if (cur) {
+ next_sg = sg_next(cur);
+ /* Check if last entry should be keeped for chainning */
+ if (!sg_is_last(next_sg) || needed_sges == 1)
+ return next_sg;
+ }
+
+ alloc_size = min_t(unsigned long, needed_sges, SG_MAX_SINGLE_ALLOC);
+ new_sg = sg_kmalloc(alloc_size, gfp_mask);
+ if (!new_sg)
+ return ERR_PTR(-ENOMEM);
+ sg_init_table(new_sg, alloc_size);
+ if (cur) {
+ __sg_chain(next_sg, new_sg);
+ table->orig_nents += alloc_size - 1;
+ } else {
+ table->sgl = new_sg;
+ table->orig_nents = alloc_size;
+ table->nents = 0;
+ }
+ return new_sg;
+}
+
/**
* __sg_alloc_table_from_pages - Allocate and initialize an sg table from
* an array of pages
@@ -374,29 +405,63 @@ EXPORT_SYMBOL(sg_alloc_table);
* @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)
+ * @prv: Last populated sge in sgt
+ * @left_pages: Left pages caller have to set after this call
* @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 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.
+ * Description:
+ * If @prv is NULL, allocate and initialize an sg table from a list of pages,
+ * else reuse the scatterlist passed in at @prv.
+ * Contiguous ranges of the pages are squashed into a single scatterlist
+ * entry up to the maximum size specified in @max_segment. A user may
+ * provide an offset at a start and a size of valid data in a buffer
+ * specified by the page array.
*
* Returns:
- * 0 on success, negative error on failure
+ * Last SGE in sgt on success, PTR_ERR on otherwise.
+ * The allocation in @sgt must be released by sg_free_table.
+ *
+ * Notes:
+ * If this function returns non-0 (eg failure), the caller must call
+ * sg_free_table() to cleanup any leftover allocations.
*/
-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)
+struct scatterlist *__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,
+ struct scatterlist *prv, unsigned int left_pages,
+ gfp_t gfp_mask)
{
- unsigned int chunks, cur_page, seg_len, i;
- int ret;
- struct scatterlist *s;
+ unsigned int chunks, cur_page, seg_len, i, prv_len = 0;
+ unsigned int added_nents = 0;
+ struct scatterlist *s = prv;
if (WARN_ON(!max_segment || offset_in_page(max_segment)))
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
+
+ if (IS_ENABLED(CONFIG_ARCH_NO_SG_CHAIN) && prv)
+ return ERR_PTR(-EOPNOTSUPP);
+
+ if (prv) {
+ unsigned long paddr = (page_to_pfn(sg_page(prv)) * PAGE_SIZE +
+ prv->offset + prv->length) /
+ PAGE_SIZE;
+
+ if (WARN_ON(offset))
+ return ERR_PTR(-EINVAL);
+
+ /* Merge contiguous pages into the last SG */
+ prv_len = prv->length;
+ while (n_pages && page_to_pfn(pages[0]) == paddr) {
+ if (prv->length + PAGE_SIZE > max_segment)
+ break;
+ prv->length += PAGE_SIZE;
+ paddr++;
+ pages++;
+ n_pages--;
+ }
+ if (!n_pages)
+ goto out;
+ }
/* compute number of contiguous chunks */
chunks = 1;
@@ -410,13 +475,9 @@ int __sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
}
}
- ret = sg_alloc_table(sgt, chunks, gfp_mask);
- if (unlikely(ret))
- return ret;
-
/* merging chunks and putting them into the scatterlist */
cur_page = 0;
- for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
+ for (i = 0; i < chunks; i++) {
unsigned int j, chunk_size;
/* look for the end of the current chunk */
@@ -429,15 +490,30 @@ int __sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
break;
}
+ /* Pass how many chunks might be left */
+ s = get_next_sg(sgt, s, chunks - i + left_pages, gfp_mask);
+ if (IS_ERR(s)) {
+ /*
+ * Adjust entry length to be as before function was
+ * called.
+ */
+ if (prv)
+ prv->length = prv_len;
+ return s;
+ }
chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
sg_set_page(s, pages[cur_page],
min_t(unsigned long, size, chunk_size), offset);
+ added_nents++;
size -= chunk_size;
offset = 0;
cur_page = j;
}
-
- return 0;
+ sgt->nents += added_nents;
+out:
+ if (!left_pages)
+ sg_mark_end(s);
+ return s;
}
EXPORT_SYMBOL(__sg_alloc_table_from_pages);
@@ -465,8 +541,9 @@ 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);
+ return PTR_ERR_OR_ZERO(__sg_alloc_table_from_pages(sgt, pages, n_pages,
+ offset, size, SCATTERLIST_MAX_SEGMENT,
+ NULL, 0, gfp_mask));
}
EXPORT_SYMBOL(sg_alloc_table_from_pages);
@@ -55,14 +55,13 @@ int main(void)
for (i = 0, test = tests; test->expected_segments; test++, i++) {
struct page *pages[MAX_PAGES];
struct sg_table st;
- int ret;
+ struct scatterlist *sg;
set_pages(pages, test->pfn, test->num_pages);
- ret = __sg_alloc_table_from_pages(&st, pages, test->num_pages,
- 0, test->size, test->max_seg,
- GFP_KERNEL);
- assert(ret == test->alloc_ret);
+ sg = __sg_alloc_table_from_pages(&st, pages, test->num_pages, 0,
+ test->size, test->max_seg, NULL, 0, GFP_KERNEL);
+ assert(PTR_ERR_OR_ZERO(sg) == test->alloc_ret);
if (test->alloc_ret)
continue;