From patchwork Fri Apr 27 17:07:09 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anatoly Burakov X-Patchwork-Id: 39136 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 7641CD4AA; Fri, 27 Apr 2018 19:07:47 +0200 (CEST) Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by dpdk.org (Postfix) with ESMTP id 78FB2AAF1 for ; Fri, 27 Apr 2018 19:07:15 +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 orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 27 Apr 2018 10:07:14 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.49,335,1520924400"; d="scan'208";a="35778592" Received: from irvmail001.ir.intel.com ([163.33.26.43]) by fmsmga008.fm.intel.com with ESMTP; 27 Apr 2018 10:07:12 -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 w3RH7CAi026453; Fri, 27 Apr 2018 18:07:12 +0100 Received: from sivswdev01.ir.intel.com (localhost [127.0.0.1]) by sivswdev01.ir.intel.com with ESMTP id w3RH7CUl023554; Fri, 27 Apr 2018 18:07:12 +0100 Received: (from aburakov@localhost) by sivswdev01.ir.intel.com with LOCAL id w3RH7Cfk023546; Fri, 27 Apr 2018 18:07:12 +0100 From: Anatoly Burakov To: dev@dpdk.org Cc: thomas@monjalon.net, bruce.richardson@intel.com, anatoly.burakov@intel.com Date: Fri, 27 Apr 2018 18:07:09 +0100 Message-Id: <437feb67375bd2e52f66cce8b33e01c55f03160b.1524848343.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 v4 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 a40cfd3..672a1be 100644 --- a/lib/librte_eal/linuxapp/eal/eal_memalloc.c +++ b/lib/librte_eal/linuxapp/eal/eal_memalloc.c @@ -504,7 +504,12 @@ alloc_seg(struct rte_memseg *ms, void *addr, int socket_id, if (!internal_config.single_file_segments) close(fd); - *(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;