tuntap: disable preemption during XDP processing
authorJason Wang <jasowang@redhat.com>
Sat, 24 Feb 2018 03:32:25 +0000 (11:32 +0800)
committerDavid S. Miller <davem@davemloft.net>
Mon, 26 Feb 2018 18:49:48 +0000 (13:49 -0500)
commit23e43f07f896f8578318cfcc9466f1e8b8ab21b6
tree00f62a532d1c824ab730820f12d42c6654a1cd52
parentf249be4d2c275fe2b98e389f471af75f758e5a59
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>
drivers/net/tun.c