From: Victor Nogueira <victor@mojatatu.com>
Date: Wed, 26 Apr 2023 15:19:40 +0000
Subject: [PATCH] net/sched: act_mirred: Add carrier check
References: bsc#1012628
Patch-mainline: 6.3.3
Git-commit: 526f28bd0fbdc699cda31426928802650c1528e5

[ Upstream commit 526f28bd0fbdc699cda31426928802650c1528e5 ]

There are cases where the device is adminstratively UP, but operationally
down. For example, we have a physical device (Nvidia ConnectX-6 Dx, 25Gbps)
who's cable was pulled out, here is its ip link output:

5: ens2f1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN mode DEFAULT group default qlen 1000
    link/ether b8:ce:f6:4b:68:35 brd ff:ff:ff:ff:ff:ff
    altname enp179s0f1np1

As you can see, it's administratively UP but operationally down.
In this case, sending a packet to this port caused a nasty kernel hang (so
nasty that we were unable to capture it). Aborting a transmit based on
operational status (in addition to administrative status) fixes the issue.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Victor Nogueira <victor@mojatatu.com>
v1->v2: Add fixes tag
v2->v3: Remove blank line between tags + add change log, suggested by Leon
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 net/sched/act_mirred.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index 8037ec9b..a61482c5 100644
--- a/net/sched/act_mirred.c
+++ b/net/sched/act_mirred.c
@@ -264,7 +264,7 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb,
 		goto out;
 	}
 
-	if (unlikely(!(dev->flags & IFF_UP))) {
+	if (unlikely(!(dev->flags & IFF_UP)) || !netif_carrier_ok(dev)) {
 		net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
 				       dev->name);
 		goto out;
-- 
2.35.3