diff options
| author | Arjun Roy <arjunroy@google.com> | 2020-10-23 20:47:09 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2020-10-24 04:11:20 +0200 |
| commit | 435ccfa894e35e3d4a1799e6ac030e48a7b69ef5 (patch) | |
| tree | f0674f64461ee9997fcad0c1616433ddcb8835a8 /COPYING | |
| parent | net: ucc_geth: Drop extraneous parentheses in comparison (diff) | |
| download | linux-435ccfa894e35e3d4a1799e6ac030e48a7b69ef5.tar.xz linux-435ccfa894e35e3d4a1799e6ac030e48a7b69ef5.zip | |
tcp: Prevent low rmem stalls with SO_RCVLOWAT.
With SO_RCVLOWAT, under memory pressure,
it is possible to enter a state where:
1. We have not received enough bytes to satisfy SO_RCVLOWAT.
2. We have not entered buffer pressure (see tcp_rmem_pressure()).
3. But, we do not have enough buffer space to accept more packets.
In this case, we advertise 0 rwnd (due to #3) but the application does
not drain the receive queue (no wakeup because of #1 and #2) so the
flow stalls.
Modify the heuristic for SO_RCVLOWAT so that, if we are advertising
rwnd<=rcv_mss, force a wakeup to prevent a stall.
Without this patch, setting tcp_rmem to 6143 and disabling TCP
autotune causes a stalled flow. With this patch, no stall occurs. This
is with RPC-style traffic with large messages.
Fixes: 03f45c883c6f ("tcp: avoid extra wakeups for SO_RCVLOWAT users")
Signed-off-by: Arjun Roy <arjunroy@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20201023184709.217614-1-arjunroy.kdev@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'COPYING')
0 files changed, 0 insertions, 0 deletions