From patchwork Wed Oct 11 09:59:07 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bruce Richardson X-Patchwork-Id: 30112 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 CD9317D34; Wed, 11 Oct 2017 11:59:53 +0200 (CEST) Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by dpdk.org (Postfix) with ESMTP id 12F3E378B for ; Wed, 11 Oct 2017 11:59:51 +0200 (CEST) Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Oct 2017 02:59:50 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,360,1503385200"; d="scan'208";a="161820292" Received: from silpixa00399126.ir.intel.com (HELO silpixa00399126.ger.corp.intel.com) ([10.237.223.223]) by fmsmga006.fm.intel.com with ESMTP; 11 Oct 2017 02:59:49 -0700 From: Bruce Richardson To: yliu@fridaylinux.org Cc: dev@dpdk.org, Bruce Richardson , Maxime Coquelin Date: Wed, 11 Oct 2017 10:59:07 +0100 Message-Id: <20171011095907.229893-1-bruce.richardson@intel.com> X-Mailer: git-send-email 2.13.6 Subject: [dpdk-dev] [PATCH] vhost: fix false-positive warning from clang 5 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" When compiling with clang extra warning flags, such as used by default with meson, a warning is given in iotlb.c: ../lib/librte_vhost/iotlb.c:318:6: warning: variable 'socket' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized] This is a false positive, as the socket value will be initialized by the call to get_mempolicy in the case where the NUMA build-time flag is set, and in cases where it is not set, "if (ret)" will always be true as ret is initialized to -1 and never changed. However, this is not immediately obvious, and is perhaps a little fragile, as it will break if other code using ret is subsequently added above the call to get_mempolicy by someone unaware of this subtle dependency. Therefore, we can fix the warning and making the code more robust by explicitly initializing socket to zero, and moving the extra condition check on ret into the #ifdef alongside the call to get_mempolicy which sets ret. Fixes: d012d1f293f4 ("vhost: add IOTLB helper functions") CC: Maxime Coquelin Signed-off-by: Bruce Richardson Reviewed-by: Maxime Coquelin --- lib/librte_vhost/iotlb.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/librte_vhost/iotlb.c b/lib/librte_vhost/iotlb.c index 066c37a73..6e48eaf0d 100644 --- a/lib/librte_vhost/iotlb.c +++ b/lib/librte_vhost/iotlb.c @@ -300,7 +300,7 @@ vhost_user_iotlb_init(struct virtio_net *dev, int vq_index) { char pool_name[RTE_MEMPOOL_NAMESIZE]; struct vhost_virtqueue *vq = dev->virtqueue[vq_index]; - int ret = -1, socket; + int ret = -1, socket = 0; if (vq->iotlb_pool) { /* @@ -314,9 +314,9 @@ vhost_user_iotlb_init(struct virtio_net *dev, int vq_index) #ifdef RTE_LIBRTE_VHOST_NUMA ret = get_mempolicy(&socket, NULL, 0, vq, MPOL_F_NODE | MPOL_F_ADDR); -#endif if (ret) socket = 0; +#endif rte_rwlock_init(&vq->iotlb_lock); rte_rwlock_init(&vq->iotlb_pending_lock);