From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by dpdk.org (Postfix) with ESMTP id E86888DB4 for ; Wed, 18 Apr 2018 12:37:48 +0200 (CEST) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Apr 2018 03:37:46 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,464,1517904000"; d="scan'208";a="38361160" Received: from irvmail001.ir.intel.com ([163.33.26.43]) by fmsmga002.fm.intel.com with ESMTP; 18 Apr 2018 03:37:45 -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 w3IAbiwm018454; Wed, 18 Apr 2018 11:37:44 +0100 Received: from sivswdev01.ir.intel.com (localhost [127.0.0.1]) by sivswdev01.ir.intel.com with ESMTP id w3IAbiLP015803; Wed, 18 Apr 2018 11:37:44 +0100 Received: (from aburakov@localhost) by sivswdev01.ir.intel.com with LOCAL id w3IAbifI015798; Wed, 18 Apr 2018 11:37:44 +0100 From: Anatoly Burakov To: dev@dpdk.org Cc: thomas@monjalon.net, anatoly.burakov@intel.com Date: Wed, 18 Apr 2018 11:37:41 +0100 Message-Id: <3f3540d70140650eb4d4ddf7370e155d0a120a58.1524047073.git.anatoly.burakov@intel.com> X-Mailer: git-send-email 1.7.0.7 In-Reply-To: References: In-Reply-To: References: Subject: [dpdk-dev] [PATCH v2 08/10] 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: , X-List-Received-Date: Wed, 18 Apr 2018 10:37:49 -0000 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 --- 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; -- 2.7.4