Hi everyone,
This series tries to fix a deadlock in virtio-net when binding/unbinding
XDP program, XDP socket or resizing the rx queue.
When pausing rx (e.g. set up xdp, xsk pool, rx resize), we call
napi_disable() on the receive queue's napi. In delayed refill_work, it
also calls napi_disable() on the receive queue's napi. When
napi_disable() is called on an already disabled napi, it will sleep in
napi_disable_locked while still holding the netdev_lock. As a result,
later napi_enable gets stuck too as it cannot acquire the netdev_lock.
This leads to refill_work and the pause-then-resume tx are stuck
altogether.
This scenario can be reproducible by binding a XDP socket to virtio-net
interface without setting up the fill ring. As a result, try_fill_recv
will fail until the fill ring is set up and refill_work is scheduled.
This fix adds virtnet_rx_(pause/resume)_all helpers and fixes up the
virtnet_rx_resume to disable future and cancel all inflights delayed
refill_work before calling napi_disable() to pause the rx.
Version 2 changes:
- Add selftest for deadlock scenario
Thanks,
Quang Minh.
Bui Quang Minh (3):
virtio-net: disable delayed refill when pausing rx
selftests: net: move xdp_helper to net/lib
selftests: net: add a virtio_net deadlock selftest
drivers/net/virtio_net.c | 60 ++++++++++++++++---
tools/testing/selftests/Makefile | 2 +-
tools/testing/selftests/drivers/net/Makefile | 2 -
tools/testing/selftests/drivers/net/queues.py | 4 +-
.../selftests/drivers/net/virtio_net/Makefile | 2 +
.../selftests/drivers/net/virtio_net/config | 1 +
.../drivers/net/virtio_net/lib/py/__init__.py | 16 +++++
.../drivers/net/virtio_net/xsk_pool.py | 52 ++++++++++++++++
tools/testing/selftests/net/lib/.gitignore | 1 +
tools/testing/selftests/net/lib/Makefile | 1 +
.../{drivers/net => net/lib}/xdp_helper.c | 0
11 files changed, 127 insertions(+), 14 deletions(-)
create mode 100644
tools/testing/selftests/drivers/net/virtio_net/lib/py/__init__.py
create mode 100755 tools/testing/selftests/drivers/net/virtio_net/xsk_pool.py
rename tools/testing/selftests/{drivers/net => net/lib}/xdp_helper.c (100%)
--
2.43.0
