From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vitaly Kuznetsov Subject: [PATCH net] hv_netvsc: Restore needed_headroom request Date: Fri, 5 Feb 2016 17:29:08 +0100 Message-ID: <1454689748-29095-1-git-send-email-vkuznets@redhat.com> Cc: devel@linuxdriverproject.org, linux-kernel@vger.kernel.org, "K. Y. Srinivasan" , Haiyang Zhang To: netdev@vger.kernel.org Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Commit c0eb454034aa ("hv_netvsc: Don't ask for additional head room in the skb") got rid of needed_headroom setting for the driver. With the change I hit the following issue trying to use ptkgen module: [ 57.522021] kernel BUG at net/core/skbuff.c:1128! [ 57.522021] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC ... [ 58.721068] Call Trace: [ 58.721068] [] netvsc_start_xmit+0x4c6/0x8e0 [hv_netvsc] ... [ 58.721068] [] ? pktgen_finalize_skb+0x25c/0x2a0 [pktgen] [ 58.721068] [] ? __netdev_alloc_skb+0xc0/0x100 [ 58.721068] [] pktgen_thread_worker+0x257/0x1920 [pktgen] Basically, we're calling skb_cow_head(skb, RNDIS_AND_PPI_SIZE) and crash on if (skb_shared(skb)) BUG(); We probably need to restore needed_headroom setting (but shrunk to RNDIS_AND_PPI_SIZE as we don't need more) to request the required headroom space. In theory, it should not give us performance penalty. Signed-off-by: Vitaly Kuznetsov --- drivers/net/hyperv/netvsc_drv.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index 1d3a665..98e34fe 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -1089,6 +1089,9 @@ static int netvsc_probe(struct hv_device *dev, net->ethtool_ops = ðtool_ops; SET_NETDEV_DEV(net, &dev->device); + /* We always need headroom for rndis header */ + net->needed_headroom = RNDIS_AND_PPI_SIZE; + /* Notify the netvsc driver of the new device */ memset(&device_info, 0, sizeof(device_info)); device_info.ring_size = ring_size; -- 2.5.0