From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Coquelin Subject: Re: [PATCH 1/8] net/virtio: revert "virtio: fix restart" Date: Fri, 4 Nov 2016 09:10:19 +0100 Message-ID: References: <1478189400-14606-1-git-send-email-yuanhan.liu@linux.intel.com> <1478189400-14606-2-git-send-email-yuanhan.liu@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: stable@dpdk.org, Ilya Maximets To: Yuanhan Liu , dev@dpdk.org Return-path: In-Reply-To: <1478189400-14606-2-git-send-email-yuanhan.liu@linux.intel.com> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 11/03/2016 05:09 PM, Yuanhan Liu wrote: > This reverts commit 9a0615af7746 ("virtio: fix restart"); conflict is > manually addressed. > > Kyle reported an issue with above commit > > qemu-kvm: Guest moved used index from 5 to 1 > > with following steps, > > 1) Start my virtio interfaces > 2) Send some traffic into/out of the interfaces > 3) Stop the interfaces > 4) Start the interfaces > 5) Send some more traffic > > And here are some quotes from Kyle's analysis, > > Prior to the patch, if an interface were stopped then started, without > restarting the application, the queues would be left as-is, because > hw->started would be set to 1. Now, calling stop sets hw->started to 0, > which means the next call to start will "touch the queues". This is the > unintended side-effect that causes the problem. > > Fixes: 9a0615af7746 ("virtio: fix restart") > > Cc: Jianfeng Tan > Cc: > Reported-by: Kyle Larose > Signed-off-by: Yuanhan Liu Reviewed-by: Maxime Coquelin Thanks, Maxime