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| author | Paolo Abeni <pabeni@redhat.com> | 2023-12-04 17:08:05 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-12-13 18:45:07 +0100 |
| commit | e4a2a4328c85f1830c8caf5bc8fa566057404fe6 (patch) | |
| tree | 605897ff85e0e2a574a3fe987ab65cd10bcdf51e /net/ipv4 | |
| parent | dc903ddc826f020baf193d8befb6c822baa530e3 (diff) | |
| download | linux-stable-e4a2a4328c85f1830c8caf5bc8fa566057404fe6.tar.gz linux-stable-e4a2a4328c85f1830c8caf5bc8fa566057404fe6.tar.bz2 linux-stable-e4a2a4328c85f1830c8caf5bc8fa566057404fe6.zip | |
tcp: fix mid stream window clamp.
[ Upstream commit 58d3aade20cdddbac6c9707ac0f3f5f8c1278b74 ]
After the blamed commit below, if the user-space application performs
window clamping when tp->rcv_wnd is 0, the TCP socket will never be
able to announce a non 0 receive window, even after completely emptying
the receive buffer and re-setting the window clamp to higher values.
Refactor tcp_set_window_clamp() to address the issue: when the user
decreases the current clamp value, set rcv_ssthresh according to the
same logic used at buffer initialization, but ensuring reserved mem
provisioning.
To avoid code duplication factor-out the relevant bits from
tcp_adjust_rcv_ssthresh() in a new helper and reuse it in the above
scenario.
When increasing the clamp value, give the rcv_ssthresh a chance to grow
according to previously implemented heuristic.
Fixes: 3aa7857fe1d7 ("tcp: enable mid stream window clamp")
Reported-by: David Gibson <david@gibson.dropbear.id.au>
Reported-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/705dad54e6e6e9a010e571bf58e0b35a8ae70503.1701706073.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/tcp.c | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 3d3a24f79573..ec46d74c2093 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3368,9 +3368,25 @@ int tcp_set_window_clamp(struct sock *sk, int val) return -EINVAL; tp->window_clamp = 0; } else { - tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ? - SOCK_MIN_RCVBUF / 2 : val; - tp->rcv_ssthresh = min(tp->rcv_wnd, tp->window_clamp); + u32 new_rcv_ssthresh, old_window_clamp = tp->window_clamp; + u32 new_window_clamp = val < SOCK_MIN_RCVBUF / 2 ? + SOCK_MIN_RCVBUF / 2 : val; + + if (new_window_clamp == old_window_clamp) + return 0; + + tp->window_clamp = new_window_clamp; + if (new_window_clamp < old_window_clamp) { + /* need to apply the reserved mem provisioning only + * when shrinking the window clamp + */ + __tcp_adjust_rcv_ssthresh(sk, tp->window_clamp); + + } else { + new_rcv_ssthresh = min(tp->rcv_wnd, tp->window_clamp); + tp->rcv_ssthresh = max(new_rcv_ssthresh, + tp->rcv_ssthresh); + } } return 0; } |