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authorGleb Smirnoff <glebius@FreeBSD.org>2025-01-13 18:13:54 +0000
committerGleb Smirnoff <glebius@FreeBSD.org>2025-01-13 18:13:54 +0000
commit1043b36b2054ffb32aadfe1c276684bf463db59a (patch)
treeca8c71e641782804aac35a3f28d2e304cb253dea
parentb84f41b4e82df373f8e682d45791b6ab636cd94e (diff)
tcp: don't send beyond receivers advertised window
When calculating length of data to be sent, we may do some congestion calculations, but we shall never send a byte beyond (snd_una + snd_wnd). In 7dc78150c730e we started to use tcp_compute_pipe() instead of (snd_wnd - off). This function makes an estimate of how much data is in flight. It can return a value smaller and larger than (snd_nxt - snd_una). It will return a value larger when we have retransmitted some data from SACK holes, and smaller once those retransmitted SACK holes are acked. We may use tcp_compute_pipe() for length calculation, but always capped by the send offset 'off', which (snd_nxt - snd_una). PR: 283649 Reviewed by: rscheff Differential Revision: https://reviews.freebsd.org/D48237 Fixes: 7dc78150c730e90fa2afdaba3aa645932b30c429
-rw-r--r--sys/netinet/tcp_output.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/sys/netinet/tcp_output.c b/sys/netinet/tcp_output.c
index 74a229012508..135e7d8493e2 100644
--- a/sys/netinet/tcp_output.c
+++ b/sys/netinet/tcp_output.c
@@ -421,8 +421,9 @@ after_sack_rexmit:
* sending new data, having retransmitted all the
* data possible in the scoreboard.
*/
- len = imin(sbavail(&so->so_snd) - off,
- sendwin - tcp_compute_pipe(tp));
+ len = imax(
+ imin(sbavail(&so->so_snd), sendwin) -
+ imax(tcp_compute_pipe(tp), off), 0);
}
}