Thread (6 messages) 6 messages, 3 authors, 2024-01-02

Re: [PATCH net] rtnetlink: allow to set iface down before enslaving it

From: Phil Sutter <phil@nwl.cc>
Date: 2024-01-01 22:31:09
Also in: stable

On Fri, Dec 29, 2023 at 11:08:35AM +0100, Nicolas Dichtel wrote:
quoted hunk ↗ jump to hunk
The below commit adds support for:
quoted
ip link set dummy0 down
ip link set dummy0 master bond0 up
but breaks the opposite:
quoted
ip link set dummy0 up
ip link set dummy0 master bond0 down
Let's add a workaround to have both commands working.

Cc: stable@vger.kernel.org
Fixes: a4abfa627c38 ("net: rtnetlink: Enslave device before bringing it up")
Signed-off-by: Nicolas Dichtel <redacted>
---
 net/core/rtnetlink.c | 8 ++++++++
 1 file changed, 8 insertions(+)
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index e8431c6c8490..dd79693c2d91 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2905,6 +2905,14 @@ static int do_setlink(const struct sk_buff *skb,
 		call_netdevice_notifiers(NETDEV_CHANGEADDR, dev);
 	}
 
+	/* Backward compat: enable to set interface down before enslaving it */
+	if (!(ifm->ifi_flags & IFF_UP) && ifm->ifi_change & IFF_UP) {
+		err = dev_change_flags(dev, rtnl_dev_combine_flags(dev, ifm),
+				       extack);
+		if (err < 0)
+			goto errout;
+	}
+
 	if (tb[IFLA_MASTER]) {
 		err = do_set_master(dev, nla_get_u32(tb[IFLA_MASTER]), extack);
 		if (err)
Doesn't this merely revert to the old behaviour of setting the interface
up before enslaving if both IFF_UP and IFLA_MASTER are present? Did you
test this with a bond-type master?

Cheers, Phil
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