[net PATCH 0/3] Fix two teardown bugs for BPF maps cpumap and devmap

[Jesper Dangaard Brouer <brouer@redhat.com>]

Removing entries from cpumap and devmap, goes through a number of
syncronization steps to make sure no new xdp_frames can be enqueued.
But there is a small chance, that xdp_frames remains which have not
been flushed/processed yet.  Flushing these during teardown, happens
from RCU context and not as usual under RX NAPI context.

The optimization introduced in commt 389ab7f01af9 ("xdp: introduce
xdp_return_frame_rx_napi"), missed that the flush operation can also
be called from RCU context.  Thus, we cannot always use the
xdp_return_frame_rx_napi call, which take advantage of the protection
provided by XDP RX running under NAPI protection.

The samples/bpf xdp_redirect_cpu have a --stress-mode, that is
adjusted to easier reproduce (verified by Red Hat QA).

---

Jesper Dangaard Brouer (3):
      xdp: fix bug in cpumap teardown code path
      samples/bpf: xdp_redirect_cpu adjustment to reproduce teardown race easier
      xdp: fix bug in devmap teardown code path


 kernel/bpf/cpumap.c                 |   15 +++++++++------
 kernel/bpf/devmap.c                 |   14 +++++++++-----
 samples/bpf/xdp_redirect_cpu_kern.c |    2 +-
 samples/bpf/xdp_redirect_cpu_user.c |    4 ++--
 4 files changed, 21 insertions(+), 14 deletions(-)