From: Maor Gottlieb <ma...@nvidia.com> In order to support dynamic allocation of SG table, this patch introduces sg_alloc_next. This function should be called to add more entries to the table. In order to share the code, we will do the following: * Extract the allocation code from __sg_alloc_table to sg_alloc. * Add a function to chain SGE to the next page.
Signed-off-by: Maor Gottlieb <ma...@nvidia.com> Signed-off-by: Leon Romanovsky <leo...@nvidia.com> --- include/linux/scatterlist.h | 29 ++++++---- lib/scatterlist.c | 110 ++++++++++++++++++++++++------------ 2 files changed, 91 insertions(+), 48 deletions(-) diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 45cf7b69d852..9d13004334aa 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -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); } /** diff --git a/lib/scatterlist.c b/lib/scatterlist.c index 292e785d21ee..ade5c4a6fbf9 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -242,38 +242,15 @@ void sg_free_table(struct sg_table *table) } EXPORT_SYMBOL(sg_free_table); -/** - * __sg_alloc_table - Allocate and initialize an sg table with given allocator - * @table: The sg table header to use - * @nents: Number of entries in sg list - * @max_ents: The maximum number of entries the allocator returns per call - * @nents_first_chunk: Number of entries int the (preallocated) first - * scatterlist chunk, 0 means no such preallocated chunk provided by user - * @gfp_mask: GFP allocation mask - * @alloc_fn: Allocator to use - * - * Description: - * This function returns a @table @nents long. The allocator is - * defined to return scatterlist chunks of maximum size @max_ents. - * Thus if @nents is bigger than @max_ents, the scatterlists will be - * chained in units of @max_ents. - * - * 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(struct sg_table *table, unsigned int nents, - unsigned int max_ents, struct scatterlist *first_chunk, - unsigned int nents_first_chunk, gfp_t gfp_mask, - sg_alloc_fn *alloc_fn) +static int sg_alloc(struct sg_table *table, struct scatterlist *prv, + unsigned int nents, unsigned int max_ents, + struct scatterlist *first_chunk, + unsigned int nents_first_chunk, + gfp_t gfp_mask, sg_alloc_fn *alloc_fn) { - struct scatterlist *sg, *prv; - unsigned int left; - unsigned curr_max_ents = nents_first_chunk ?: max_ents; - unsigned prv_max_ents; - - memset(table, 0, sizeof(*table)); + unsigned int curr_max_ents = nents_first_chunk ?: max_ents; + unsigned int left, prv_max_ents = 0; + struct scatterlist *sg; if (nents == 0) return -EINVAL; @@ -283,7 +260,6 @@ int __sg_alloc_table(struct sg_table *table, unsigned int nents, #endif left = nents; - prv = NULL; do { unsigned int sg_size, alloc_size = left; @@ -308,7 +284,7 @@ int __sg_alloc_table(struct sg_table *table, unsigned int nents, * linkage. Without this, sg_kfree() may get * confused. */ - if (prv) + if (prv_max_ents) table->nents = ++table->orig_nents; return -ENOMEM; @@ -321,10 +297,17 @@ int __sg_alloc_table(struct sg_table *table, unsigned int nents, * If this is the first mapping, assign the sg table header. * If this is not the first mapping, chain previous part. */ - if (prv) - sg_chain(prv, prv_max_ents, sg); - else + if (!prv) table->sgl = sg; + else if (prv_max_ents) + sg_chain(prv, prv_max_ents, sg); + else { + __sg_chain(prv, sg); + /* We decrease one since the prvious last sge in used to + * chainning. + */ + table->nents = table->orig_nents -= 1; + } /* * If no more entries after this one, mark the end @@ -339,6 +322,61 @@ int __sg_alloc_table(struct sg_table *table, unsigned int nents, return 0; } + +/** + * sg_alloc_next - Allocate and initialize new entries in the sg table + * @table: The sg table header to use + * @last: The last scatter list entry in the table + * @nents: Number of entries in sg list + * @max_ents: The maximum number of entries the allocator returns per call + * @gfp_mask: GFP allocation mask + * @alloc_fn: Allocator to use + * + * Description: + * This function extend @table with @nents long. The allocator is + * defined to return scatterlist chunks of maximum size @max_ents. + * Thus if @nents is bigger than @max_ents, the scatterlists will be + * chained in units of @max_ents. + * + **/ +static int sg_alloc_next(struct sg_table *table, struct scatterlist *last, + unsigned int nents, unsigned int max_ents, + gfp_t gfp_mask) +{ + return sg_alloc(table, last, nents, max_ents, NULL, 0, gfp_mask, + sg_kmalloc); +} + +/** + * __sg_alloc_table - Allocate and initialize an sg table with given allocator + * @table: The sg table header to use + * @nents: Number of entries in sg list + * @max_ents: The maximum number of entries the allocator returns per call + * @nents_first_chunk: Number of entries int the (preallocated) first + * scatterlist chunk, 0 means no such preallocated chunk provided by user + * @gfp_mask: GFP allocation mask + * @alloc_fn: Allocator to use + * + * Description: + * This function returns a @table @nents long. The allocator is + * defined to return scatterlist chunks of maximum size @max_ents. + * Thus if @nents is bigger than @max_ents, the scatterlists will be + * chained in units of @max_ents. + * + * 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(struct sg_table *table, unsigned int nents, + unsigned int max_ents, struct scatterlist *first_chunk, + unsigned int nents_first_chunk, gfp_t gfp_mask, + sg_alloc_fn *alloc_fn) +{ + memset(table, 0, sizeof(*table)); + return sg_alloc(table, NULL, nents, max_ents, first_chunk, + nents_first_chunk, gfp_mask, alloc_fn); +} EXPORT_SYMBOL(__sg_alloc_table); /** -- 2.26.2