From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH] net: xen-netback: correctly restart Tx after a VM restore/migrate Date: Fri, 30 Sep 2011 17:45:05 +0100 Message-ID: <1317401105.26672.319.camel@zakaz.uk.xensource.com> References: <1317400671-21236-1-git-send-email-david.vrabel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" , "xen-devel@lists.xensource.com" , "David S. Miller" To: David Vrabel Return-path: In-Reply-To: <1317400671-21236-1-git-send-email-david.vrabel@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com List-Id: netdev.vger.kernel.org On Fri, 2011-09-30 at 17:37 +0100, David Vrabel wrote: > If a VM is saved and restored (or migrated) the netback driver will no > longer process any Tx packets from the frontend. xenvif_up() does not > schedule the processing of any pending Tx requests from the front end > because the carrier is off. Without this initial kick the frontend > just adds Tx requests to the ring without raising an event (until the > ring is full). > > This was caused by 47103041e91794acdbc6165da0ae288d844c820b (net: > xen-netback: convert to hw_features) which reordered the calls to > xenvif_up() and netif_carrier_on() in xenvif_connect(). Ah, so the bit of that patch which moved "netif_carrier_on(vif->dev);" should have actually moved the entire block netif_carrier_on(vif->dev); if (netif_running(vif->dev)) xenvif_up(vif); Since it it is logically a single thing. Make sense. Thanks! > Signed-off-by: David Vrabel Acked-by: Ian Campbell Ian. > --- > drivers/net/xen-netback/interface.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c > index 0ca86f9..1825629 100644 > --- a/drivers/net/xen-netback/interface.c > +++ b/drivers/net/xen-netback/interface.c > @@ -327,12 +327,12 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref, > xenvif_get(vif); > > rtnl_lock(); > - if (netif_running(vif->dev)) > - xenvif_up(vif); > if (!vif->can_sg && vif->dev->mtu > ETH_DATA_LEN) > dev_set_mtu(vif->dev, ETH_DATA_LEN); > netdev_update_features(vif->dev); > netif_carrier_on(vif->dev); > + if (netif_running(vif->dev)) > + xenvif_up(vif); > rtnl_unlock(); > > return 0;