From: stephen hemminger Date: Wed, 11 Jan 2017 17:16:32 +0000 (-0800) Subject: netvsc: add rcu_read locking to netvsc callback X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=5b3df4401064ef94cddac976aba1474a7050fa5e;p=linux-beck.git netvsc: add rcu_read locking to netvsc callback [ Upstream commit 0719e72ccb801829a3d735d187ca8417f0930459 ] The receive callback (in tasklet context) is using RCU to get reference to associated VF network device but this is not safe. RCU read lock needs to be held. Found by running with full lockdep debugging enabled. Fixes: f207c10d9823 ("hv_netvsc: use RCU to protect vf_netdev") Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index c9140c3aeb67..ff038e507fd6 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -659,6 +659,7 @@ int netvsc_recv_callback(struct hv_device *device_obj, * policy filters on the host). Deliver these via the VF * interface in the guest. */ + rcu_read_lock(); vf_netdev = rcu_dereference(net_device_ctx->vf_netdev); if (vf_netdev && (vf_netdev->flags & IFF_UP)) net = vf_netdev; @@ -667,6 +668,7 @@ int netvsc_recv_callback(struct hv_device *device_obj, skb = netvsc_alloc_recv_skb(net, packet, csum_info, *data, vlan_tci); if (unlikely(!skb)) { ++net->stats.rx_dropped; + rcu_read_unlock(); return NVSP_STAT_FAIL; } @@ -696,6 +698,7 @@ int netvsc_recv_callback(struct hv_device *device_obj, * TODO - use NAPI? */ netif_rx(skb); + rcu_read_unlock(); return 0; }