linux-kernel - [PATCH net-next 1/2] openvswitch: Fix double reporting of drops in dropwatch

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Date:   Thu, 28 Jul 2022 12:12:58 -0400
From:   Mike Pattrick <mkp@...hat.com>
To:     netdev@...r.kernel.org
Cc:     pvalerio@...hat.com, Mike Pattrick <mkp@...hat.com>,
        Pravin B Shelar <pshelar@....org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, dev@...nvswitch.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH net-next 1/2] openvswitch: Fix double reporting of drops in dropwatch

Frames sent to userspace can be reported as dropped in
ovs_dp_process_packet, however, if they are dropped in the netlink code
then netlink_attachskb will report the same frame as dropped.

This patch checks for error codes which indicate that the frame has
already been freed.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2109946
Signed-off-by: Mike Pattrick <mkp@...hat.com>
---
 net/openvswitch/datapath.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 7e8a39a35627..029f9c3e1c28 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -252,10 +252,20 @@ void ovs_dp_process_packet(struct sk_buff *skb, struct sw_flow_key *key)
 
 		upcall.mru = OVS_CB(skb)->mru;
 		error = ovs_dp_upcall(dp, skb, key, &upcall, 0);
-		if (unlikely(error))
-			kfree_skb(skb);
-		else
+		switch (error) {
+		case 0:
+			fallthrough;
+		case -EAGAIN:
+			fallthrough;
+		case -ERESTARTSYS:
+			fallthrough;
+		case -EINTR:
 			consume_skb(skb);
+			break;
+		default:
+			kfree_skb(skb);
+			break;
+		}
 		stats_counter = &stats->n_missed;
 		goto out;
 	}
-- 
2.31.1