This is an update version of last version to fix the handling of polling errors
in vhost/vhost_net.

Currently, vhost and vhost_net ignore polling errors which can lead kernel
crashing when it tries to remove itself from waitqueue after the polling
failure. Fix this by checking the poll->wqh before the removing and report an
error when meet polling errors.

Changes from v2:
- check poll->wqh instead of the wrong assumption about POLLERR and waitqueue
- drop the whole tx polling state check since it was replaced by the wqh
  checking
- drop the buggy tuntap patch

Changes from v1:
- restore the state before the ioctl when vhost_init_used() fails
- log the error when meet polling errors in the data path
- don't put into waitqueue when tun_chr_poll() return POLLERR

Jason Wang (2):
  vhost_net: correct error handling in vhost_net_set_backend()
  vhost: handle polling errors

 drivers/vhost/net.c   |   88 +++++++++++++++++++-----------------------------
 drivers/vhost/vhost.c |   31 +++++++++++++----
 drivers/vhost/vhost.h |    2 +-
 3 files changed, 59 insertions(+), 62 deletions(-)