tree 00f62a532d1c824ab730820f12d42c6654a1cd52
parent f249be4d2c275fe2b98e389f471af75f758e5a59
author Jason Wang <jasowang@redhat.com> 1519443145 +0800
committer David S. Miller <davem@davemloft.net> 1519670988 -0500

tuntap: disable preemption during XDP processing

Except for tuntap, all other drivers' XDP was implemented at NAPI
poll() routine in a bh. This guarantees all XDP operation were done at
the same CPU which is required by e.g BFP_MAP_TYPE_PERCPU_ARRAY. But
for tuntap, we do it in process context and we try to protect XDP
processing by RCU reader lock. This is insufficient since
CONFIG_PREEMPT_RCU can preempt the RCU reader critical section which
breaks the assumption that all XDP were processed in the same CPU.

Fixing this by simply disabling preemption during XDP processing.

Fixes: 761876c857cb ("tap: XDP support")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>