From mboxrd@z Thu Jan 1 00:00:00 1970 From: Igor Ryzhov Subject: [PATCH] kni: fix rte_kni_update_link Date: Thu, 24 Jan 2019 23:47:49 +0300 Message-ID: <20190124204749.49912-1-iryzhov@nfware.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Cc: stable@dpdk.org To: dev@dpdk.org Return-path: Received: from mail-lf1-f68.google.com (mail-lf1-f68.google.com [209.85.167.68]) by dpdk.org (Postfix) with ESMTP id 31F6B91 for ; Thu, 24 Jan 2019 21:47:56 +0100 (CET) Received: by mail-lf1-f68.google.com with SMTP id a16so5348702lfg.3 for ; Thu, 24 Jan 2019 12:47:56 -0800 (PST) List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" After read, file offset must be set to 0 before write. Otherwise, the third byte will be overwritten instead of the first. Fixes: c6fd54f28c24 ("kni: add function to set link state on kernel interface") Cc: stable@dpdk.org Signed-off-by: Igor Ryzhov --- lib/librte_kni/rte_kni.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/lib/librte_kni/rte_kni.c b/lib/librte_kni/rte_kni.c index 73aeccccf..5899bb14a 100644 --- a/lib/librte_kni/rte_kni.c +++ b/lib/librte_kni/rte_kni.c @@ -746,6 +746,12 @@ rte_kni_update_link(struct rte_kni *kni, unsigned int linkup) } old_linkup = (old_carrier[0] == '1'); + if (lseek(fd, 0, SEEK_SET) == -1) { + RTE_LOG(ERR, KNI, "Failed to change file position: %s.\n", path); + close(fd); + return -1; + } + new_carrier = linkup ? "1" : "0"; ret = write(fd, new_carrier, 1); if (ret < 1) { -- 2.20.1