Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751894AbdG0JF5 (ORCPT ); Thu, 27 Jul 2017 05:05:57 -0400 Received: from mail-wr0-f193.google.com ([209.85.128.193]:36296 "EHLO mail-wr0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751451AbdG0JFP (ORCPT ); Thu, 27 Jul 2017 05:05:15 -0400 From: Tvrtko Ursulin X-Google-Original-From: Tvrtko Ursulin To: Intel-gfx@lists.freedesktop.org Cc: Ben Widawsky , Jason Ekstrand , Tvrtko Ursulin , Masahiro Yamada , linux-kernel@vger.kernel.org, Chris Wilson , Joonas Lahtinen Subject: [PATCH 3/4] lib/scatterlist: Introduce and export __sg_alloc_table_from_pages Date: Thu, 27 Jul 2017 10:05:03 +0100 Message-Id: <20170727090504.15812-4-tvrtko.ursulin@linux.intel.com> X-Mailer: git-send-email 2.9.4 In-Reply-To: <20170727090504.15812-1-tvrtko.ursulin@linux.intel.com> References: <20170727090504.15812-1-tvrtko.ursulin@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5463 Lines: 138 From: Tvrtko Ursulin Drivers like i915 benefit from being able to control the maxium size of the sg coallesced 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. Signed-off-by: Tvrtko Ursulin Cc: Masahiro Yamada Cc: linux-kernel@vger.kernel.org Cc: Chris Wilson Reviewed-by: Chris Wilson (v2) Cc: Joonas Lahtinen --- include/linux/scatterlist.h | 11 +++++---- lib/scatterlist.c | 58 +++++++++++++++++++++++++++++++++++---------- 2 files changed, 52 insertions(+), 17 deletions(-) diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 6dd2ddbc6230..874b50c232de 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -267,10 +267,13 @@ 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_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); +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); size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, size_t buflen, off_t skip, bool to_buffer); diff --git a/lib/scatterlist.c b/lib/scatterlist.c index 7b2e74da2c44..1a5900f9a057 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -370,14 +370,15 @@ 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 @@ -389,16 +390,18 @@ EXPORT_SYMBOL(sg_alloc_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, -- 2.9.4