[PATCH] Carrier detect ok, don't turn off negotiation

[Denis Du <dudenis2000@yahoo.ca>]

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In drivers/net/wan/hdlc_ppp.c, some noise on physical line can cause the carrier detect still ok, but the protocol will fail. So if carrier detect ok, don't turn off protocol negotiation

This patch is against the kernel version Linux 4.15-rc8

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From b5902a4dfc709b62b704997ab64f31c9ef69a6db Mon Sep 17 00:00:00 2001
From: Denis Du <dudenis2000@yahoo.ca>
Date: Mon, 15 Jan 2018 17:26:06 -0500
Subject: [PATCH] netdev: carrier detect ok, don't turn off negotiation

Sometimes when physical lines have a just good noise to make the protocol
handshaking fail, but the carrier detect still good. Then after remove of
the noise, nobody will trigger this protocol to be start again to cause
the link to never come back. The fix is when the carrier is still on, not
terminate the protocol handshaking.

Signed-off-by: Denis Du <dudenis2000@yahoo.ca>
---
 drivers/net/wan/hdlc_ppp.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wan/hdlc_ppp.c b/drivers/net/wan/hdlc_ppp.c
index afeca6b..ab8b3cb 100644
--- a/drivers/net/wan/hdlc_ppp.c
+++ b/drivers/net/wan/hdlc_ppp.c
@@ -574,7 +574,10 @@ static void ppp_timer(struct timer_list *t)
 			ppp_cp_event(proto->dev, proto->pid, TO_GOOD, 0, 0,
 				     0, NULL);
 			proto->restart_counter--;
-		} else
+		} else if (netif_carrier_ok(proto->dev))
+			ppp_cp_event(proto->dev, proto->pid, TO_GOOD, 0, 0,
+				     0, NULL);
+		else
 			ppp_cp_event(proto->dev, proto->pid, TO_BAD, 0, 0,
 				     0, NULL);
 		break;
-- 
2.1.4