From 14a03cf80edf3e19953bb744938e48bc9d496d30 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Fri, 5 Feb 2016 17:29:08 +0100 Subject: [PATCH] hv_netvsc: Restore needed_headroom request 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 Signed-off-by: David S. Miller --- 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 1d3a66563bac..98e34fee45c7 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; -- GitLab