From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fiona Trahe Subject: [PATCH] crypto: remove unused digest-appended feature Date: Thu, 17 Nov 2016 17:33:16 +0000 Message-ID: <1479403997-15437-1-git-send-email-fiona.trahe@intel.com> Cc: pablo.de.lara.guarch@intel.com, fiona.trahe@intel.com, john.griffin@intel.com, michalx.k.jastrzebski@intel.com, arkadiuszx.kusztal@intel.com To: dev@dpdk.org Return-path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by dpdk.org (Postfix) with ESMTP id E5360558D for ; Thu, 17 Nov 2016 18:33:27 +0100 (CET) List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" The cryptodev API had specified that if the digest address field was left empty on an authentication operation, then the PMD would assume the digest was appended to the source or destination data. This case was not handled at all by most PMDs and incorrectly handled by the QAT PMD. As no bugs were raised, it is assumed to be not needed, so this patch removes it, rather than add handling for the case on all PMDs. The digest can still be appended to the data, but its address must now be provided in the op. I've added this cover letter to pre-empt the question which will arise in chained-mbuf case. (Chained-mbuf support will be added in next few weeks for 17.02) In a chained-mbuf case, if the digest is appended to the data, it could in theory end up split across the last 2 mbufs. Using the digest address field only works for the case where the digest is in a flat buffer. The digest-appended feature would have provided one way of handling this, pushing the responsibility down to the PMD to follow the chain to find the digest address and handle it whether in 1 or 2 mbufs. However, this is adding extra cycles on the data path in all PMDs to handle a case which may not arise in many applications. The alternative is to give the application the responsibility to make sure the digest is in a flat buffer. Specifically if an application knows cases of a digest spanning buffers can arise, then it can check for this case and memcpy the partial start of the digest from the second last buffer into the last buffer so it's no longer split. Does anyone see a problem with this? Fiona Trahe (1): crypto: remove unused digest-appended feature drivers/crypto/qat/qat_adf/qat_algs_build_desc.c | 2 ++ drivers/crypto/qat/qat_crypto.c | 18 +----------------- lib/librte_cryptodev/rte_crypto_sym.h | 10 +--------- 3 files changed, 4 insertions(+), 26 deletions(-) -- 2.5.0