From patchwork Wed Apr 25 09:56:46 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anatoly Burakov X-Patchwork-Id: 38875 X-Patchwork-Delegate: thomas@monjalon.net Return-Path: X-Original-To: patchwork@dpdk.org Delivered-To: patchwork@dpdk.org Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 11B7B559A; Wed, 25 Apr 2018 11:57:16 +0200 (CEST) Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by dpdk.org (Postfix) with ESMTP id 575572F4F for ; Wed, 25 Apr 2018 11:56:51 +0200 (CEST) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Apr 2018 02:56:49 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.49,325,1520924400"; d="scan'208";a="35134183" Received: from irvmail001.ir.intel.com ([163.33.26.43]) by fmsmga008.fm.intel.com with ESMTP; 25 Apr 2018 02:56:49 -0700 Received: from sivswdev01.ir.intel.com (sivswdev01.ir.intel.com [10.237.217.45]) by irvmail001.ir.intel.com (8.14.3/8.13.6/MailSET/Hub) with ESMTP id w3P9umwB010753; Wed, 25 Apr 2018 10:56:48 +0100 Received: from sivswdev01.ir.intel.com (localhost [127.0.0.1]) by sivswdev01.ir.intel.com with ESMTP id w3P9umsb021940; Wed, 25 Apr 2018 10:56:48 +0100 Received: (from aburakov@localhost) by sivswdev01.ir.intel.com with LOCAL id w3P9um6d021936; Wed, 25 Apr 2018 10:56:48 +0100 From: Anatoly Burakov To: dev@dpdk.org Cc: thomas@monjalon.net, anatoly.burakov@intel.com Date: Wed, 25 Apr 2018 10:56:46 +0100 Message-Id: X-Mailer: git-send-email 1.7.0.7 In-Reply-To: References: In-Reply-To: References: Subject: [dpdk-dev] [PATCH v3 8/9] mem: fix statement having no effect X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Coverity reports these lines as having no effect. Technically, we do want for those lines to have no effect, however they would've likely been optimized out. Add volatile qualifiers to ensure the code has effects. Coverity issue: 272608 Fixes: 582bed1e1d1d ("mem: support mapping hugepages at runtime") Cc: anatoly.burakov@intel.com Signed-off-by: Anatoly Burakov Acked-by: Bruce Richardson --- lib/librte_eal/linuxapp/eal/eal_memalloc.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/lib/librte_eal/linuxapp/eal/eal_memalloc.c b/lib/librte_eal/linuxapp/eal/eal_memalloc.c index 6a75e5b..655c69e 100644 --- a/lib/librte_eal/linuxapp/eal/eal_memalloc.c +++ b/lib/librte_eal/linuxapp/eal/eal_memalloc.c @@ -503,7 +503,12 @@ alloc_seg(struct rte_memseg *ms, void *addr, int socket_id, (unsigned int)(alloc_sz >> 20)); goto mapped; } - *(int *)addr = *(int *)addr; + /* we need to trigger a write to the page to enforce page fault and + * ensure that page is accessible to us, but we can't overwrite value + * that is already there, so read the old value, and write itback. + * kernel populates the page with zeroes initially. + */ + *(volatile int *)addr = *(volatile int *)addr; ms->addr = addr; ms->hugepage_sz = alloc_sz;