From: LABBE Corentin Subject: [PATCH v2 5/8] lib: introduce sg_nents_len_chained Date: Fri, 18 Sep 2015 14:57:13 +0200 Message-ID: <1442581036-23789-6-git-send-email-clabbe.montjoie@gmail.com> References: <1442581036-23789-1-git-send-email-clabbe.montjoie@gmail.com> Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org To: herbert@gondor.apana.org.au, davem@davemloft.net, akpm@linux-foundation.org, arnd@arndb.de, axboe@fb.com, clabbe.montjoie@gmail.com, david.s.gordon@intel.com, martin.petersen@oracle.com, robert.jarzmik@free.fr, thomas.lendacky@amd.com, tonyb@cybernetics.com Return-path: In-Reply-To: <1442581036-23789-1-git-send-email-clabbe.montjoie@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org Some driver use a modified version of sg_nents_for_len with an additional parameter bool *chained for knowing if the scatterlist is chained or not. So, for removing duplicate code, add sg_nents_len_chained in lib/scatterlist.c Signed-off-by: LABBE Corentin --- include/linux/scatterlist.h | 1 + lib/scatterlist.c | 40 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 556ec1e..594cdb0 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -243,6 +243,7 @@ static inline void *sg_virt(struct scatterlist *sg) int sg_nents(struct scatterlist *sg); int sg_nents_for_len(struct scatterlist *sg, u64 len); +int sg_nents_len_chained(struct scatterlist *sg, u64 len, bool *chained); struct scatterlist *sg_next(struct scatterlist *); struct scatterlist *sg_last(struct scatterlist *s, unsigned int); void sg_init_table(struct scatterlist *, unsigned int); diff --git a/lib/scatterlist.c b/lib/scatterlist.c index bafa993..070e396 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -90,6 +90,46 @@ int sg_nents_for_len(struct scatterlist *sg, u64 len) EXPORT_SYMBOL(sg_nents_for_len); /** + * sg_nents_len_chained - return total count of entries in scatterlist + * needed to satisfy the supplied length + * @sg: The scatterlist + * @len: The total required length + * @chained A pointer where to store if SG is chained or not + * + * Description: + * Determines the number of entries in sg that are required to meet + * the supplied length, taking into account chaining as well + * If the scatterlist is chained, set *chained to true. + * + * Returns: + * the number of sg entries needed, negative error on failure + * + **/ +int sg_nents_len_chained(struct scatterlist *sg, u64 len, bool *chained) +{ + int nents; + u64 total; + + if (chained) + *chained = false; + + if (!len) + return 0; + + for (nents = 0, total = 0; sg; sg = sg_next(sg)) { + nents++; + total += sg->length; + if (!sg_is_last(sg) && (sg + 1)->length == 0 && chained) + *chained = true; + if (total >= len) + return nents; + } + + return -EINVAL; +} +EXPORT_SYMBOL(sg_nents_len_chained); + +/** * sg_last - return the last scatterlist entry in a list * @sgl: First entry in the scatterlist * @nents: Number of entries in the scatterlist -- 2.4.6