[PATCH v2 0/3] Fixes and a workaround for TCP stalls with small buffers

[Stefano Brivio <sbrivio@redhat.com>]

The fundamental patch here is 2/3, which is a workaround for a rather
surprising kernel behaviour we seem to be hitting. This all comes from
the investigation around https://bugs.passt.top/show_bug.cgi?id=74.

I can't hit stalls anymore and throughput looks finally good to me
(~3.5gbps with 208 KiB rmem_max and wmem_max), but... please test
(again).

v2:
- Drop 1/5 (checking for ACK before resetting STALLED and calling
  tcp_data_from_sock() directly from tcp_tap_handler())
- Moving reset of STALLED flag is now done in 2/3 (was 3/5)
- Don't pass unnecessary argument to tcp_data_to_tap() in 3/3 (was
  4/5)
- Drop 5/5 as long as we're not sure what kind of buffer clamping
  is actually beneficial

Stefano Brivio (3):
  tcp: Fix comment to tcp_sock_consume()
  tcp: Force TCP_WINDOW_CLAMP before resetting STALLED flag
  tcp, tap: Don't increase tap-side sequence counter for dropped frames

 tap.c | 10 ++++++---
 tap.h |  2 +-
 tcp.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++----------
 3 files changed, 67 insertions(+), 16 deletions(-)

-- 
2.39.2