From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by dpdk.org (Postfix) with ESMTP id 5A03011A4; Mon, 10 Sep 2018 09:48:29 +0200 (CEST) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BB2E97DAC7; Mon, 10 Sep 2018 07:48:28 +0000 (UTC) Received: from [10.36.112.19] (ovpn-112-19.ams2.redhat.com [10.36.112.19]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C8A60A30AC; Mon, 10 Sep 2018 07:48:26 +0000 (UTC) To: Tiwei Bie Cc: zhihong.wang@intel.com, dev@dpdk.org, stable@dpdk.org References: <20180904235555.31839-1-tiwei.bie@intel.com> <20180910073637.GA25254@debian> From: Maxime Coquelin Message-ID: Date: Mon, 10 Sep 2018 09:48:24 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180910073637.GA25254@debian> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Mon, 10 Sep 2018 07:48:28 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Mon, 10 Sep 2018 07:48:28 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'maxime.coquelin@redhat.com' RCPT:'' Subject: Re: [dpdk-stable] [PATCH] vhost: fix vhost interrupt support X-BeenThere: stable@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches for DPDK stable branches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 10 Sep 2018 07:48:29 -0000 On 09/10/2018 09:36 AM, Tiwei Bie wrote: > Hi Maxime, > > On Mon, Sep 10, 2018 at 09:22:00AM +0200, Maxime Coquelin wrote: >> Hi Tiwei, >> >> On 09/05/2018 01:55 AM, Tiwei Bie wrote: >>> When VIRTIO_RING_F_EVENT_IDX is negotiated, we need to >>> update the avail event to enable the notification. >>> >>> Fixes: 3f8ff12821e4 ("vhost: support interrupt mode") >>> Cc: stable@dpdk.org >>> >>> Signed-off-by: Tiwei Bie >>> --- >>> lib/librte_vhost/Makefile | 1 + >>> lib/librte_vhost/vhost.c | 18 ++++++++++++------ >>> lib/librte_vhost/vhost.h | 2 ++ >>> 3 files changed, 15 insertions(+), 6 deletions(-) >>> >>> diff --git a/lib/librte_vhost/Makefile b/lib/librte_vhost/Makefile >>> index de431fbb7..531cf4832 100644 >>> --- a/lib/librte_vhost/Makefile >>> +++ b/lib/librte_vhost/Makefile >>> @@ -13,6 +13,7 @@ LIBABIVER := 4 >>> CFLAGS += -DALLOW_EXPERIMENTAL_API >>> CFLAGS += $(WERROR_FLAGS) -I$(SRCDIR) -O3 -D_FILE_OFFSET_BITS=64 >>> CFLAGS += -I vhost_user >>> +CFLAGS += -fno-strict-aliasing >> >> I'm not clear why this is needed looking at the code below, >> could you please explain? > > Without this, we will get below build error: > > lib/librte_vhost/vhost.c: In function ‘vhost_enable_notify_split’: > lib/librte_vhost/vhost.h:656:4: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing] > (*(volatile uint16_t*)&(vr)->used->ring[(vr)->size]) > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > lib/librte_vhost/vhost.c:659:4: note: in expansion of macro ‘vhost_avail_event’ > vhost_avail_event(vq) = vq->last_avail_idx; > ^~~~~~~~~~~~~~~~~ > cc1: all warnings being treated as errors OK, thanks for the info. Reviewed-by: Maxime Coquelin Maxime