netdev - [PATCH net] ethtool: don't propagate EOPNOTSUPP from dumps

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Date: Sun, 26 Nov 2023 14:58:06 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
	edumazet@...gle.com,
	pabeni@...hat.com,
	Jakub Kicinski <kuba@...nel.org>,
	f.fainelli@...il.com,
	mkubecek@...e.cz
Subject: [PATCH net] ethtool: don't propagate EOPNOTSUPP from dumps

The default dump handler needs to clear ret before returning.
Otherwise if the last interface returns an inconsequential
error this error will propagate to user space.

This may confuse user space (ethtool CLI seems to ignore it,
but YNL doesn't). It will also terminate the dump early
for mutli-skb dump, because netlink core treats EOPNOTSUPP
as a real error.

Fixes: 728480f12442 ("ethtool: default handlers for GET requests")
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
CC: f.fainelli@...il.com
CC: mkubecek@...e.cz
---
 net/ethtool/netlink.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
index 3bbd5afb7b31..fe3553f60bf3 100644
--- a/net/ethtool/netlink.c
+++ b/net/ethtool/netlink.c
@@ -505,6 +505,7 @@ static int ethnl_default_dumpit(struct sk_buff *skb,
 				ret = skb->len;
 			break;
 		}
+		ret = 0;
 	}
 	rtnl_unlock();
 
-- 
2.42.0