From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Horman Subject: [PATCH] Don't allow sharing of tx skbs on xen-netfront Date: Mon, 14 Nov 2011 14:22:24 -0500 Message-ID: <1321298544-16434-1-git-send-email-nhorman@tuxdriver.com> Cc: Neil Horman , "David S. Miller" , Jeremy Fitzhardinge , Konrad Rzeszutek Wilk , xen-devel@lists.xensource.com To: netdev@vger.kernel.org Return-path: Received: from charlotte.tuxdriver.com ([70.61.120.58]:55707 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753733Ab1KNTWi (ORCPT ); Mon, 14 Nov 2011 14:22:38 -0500 Sender: netdev-owner@vger.kernel.org List-ID: It was pointed out to me recently that the xen-netfront driver can't safely support shared skbs on transmit, since, while it doesn't maintain skb state directly, it does pass a pointer to the skb to the hypervisor via a list, and the hypervisor may expect the contents of the skb to remain stable. Clearing the IFF_TX_SKB_SHARING flag after the call to alloc_etherdev to make it safe. Signed-off-by: Neil Horman CC: "David S. Miller" CC: Jeremy Fitzhardinge CC: Konrad Rzeszutek Wilk CC: xen-devel@lists.xensource.com --- drivers/net/xen-netfront.c | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-) diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index 226faab..fb1077b 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -1252,6 +1252,12 @@ static struct net_device * __devinit xennet_create_dev(struct xenbus_device *dev return ERR_PTR(-ENOMEM); } + /* + * Since frames remain on a queue after a return from xennet_start_xmit, + * we can't support tx shared skbs + */ + netdev->priv_flags &= ~IFF_TX_SKB_SHARING; + np = netdev_priv(netdev); np->xbdev = dev; -- 1.7.6.4