[TCP]: Make invariant check complain about invalid sacked_out

Earlier resolution for NewReno's sacked_out should now keep
it small enough for this to become invariant-like check.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 4 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 722c9cbb91e3..41f4b862319d 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2504,11 +2504,8 @@ tcp_fastretrans_alert(struct sock *sk, int pkts_acked, int flag)
                                     (tcp_fackets_out(tp) > tp->reordering));
         int fast_rexmit = 0;
 
-        /* Some technical things:
-         * 1. Reno does not count dupacks (sacked_out) automatically. */
-        if (!tp->packets_out)
+        if (WARN_ON(!tp->packets_out && tp->sacked_out))
                 tp->sacked_out = 0;
-
         if (WARN_ON(!tp->sacked_out && tp->fackets_out))
                 tp->fackets_out = 0;