netdev - Re: [PATCH net v2 1/4] bonding: add bond_ether

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Message-ID: <28497.1678808095@famine>
Date:   Tue, 14 Mar 2023 08:34:55 -0700
From:   Jay Vosburgh <jay.vosburgh@...onical.com>
To:     Nikolay Aleksandrov <razor@...ckwall.org>
cc:     netdev@...r.kernel.org, monis@...taire.com, syoshida@...hat.com,
        andy@...yhouse.net, kuba@...nel.org, davem@...emloft.net,
        pabeni@...hat.com, edumazet@...gle.com,
        syzbot+9dfc3f3348729cc82277@...kaller.appspotmail.com
Subject: Re: [PATCH net v2 1/4] bonding: add bond_ether_setup helper

Nikolay Aleksandrov <razor@...ckwall.org> wrote:

>Add bond_ether_setup helper which will be used in the following patches
>to fix all ether_setup() calls in the bonding driver. It takes care of both
>IFF_MASTER and IFF_SLAVE flags, the former is always restored and the
>latter only if it was set.
>
>Fixes: e36b9d16c6a6d ("bonding: clean muticast addresses when device changes type")
>Fixes: 7d5cd2ce5292 ("bonding: correctly handle bonding type change on enslave failure")
>Signed-off-by: Nikolay Aleksandrov <razor@...ckwall.org>
>---
> drivers/net/bonding/bond_main.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
>diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>index 00646aa315c3..d41024ad2c18 100644
>--- a/drivers/net/bonding/bond_main.c
>+++ b/drivers/net/bonding/bond_main.c
>@@ -1775,6 +1775,18 @@ void bond_lower_state_changed(struct slave *slave)
> 		slave_err(bond_dev, slave_dev, "Error: %s\n", errmsg);	\
> } while (0)
> 
>+/* ether_setup() resets bond_dev's flags so we always have to restore
>+ * IFF_MASTER, and only restore IFF_SLAVE if it was set
>+ */
>+static void bond_ether_setup(struct net_device *bond_dev)
>+{
>+	unsigned int slave_flag = bond_dev->flags & IFF_SLAVE;
>+
>+	ether_setup(bond_dev);
>+	bond_dev->flags |= IFF_MASTER | slave_flag;
>+	bond_dev->priv_flags &= ~IFF_TX_SKB_SHARING;
>+}

	Is setting IFF_MASTER always correct here?  I note that patch #2
is replacing code that does not set IFF_MASTER, whereas patch #3 is
replacing code that does set IFF_MASTER.

	Presuming that this is the desired behavior, perhaps mention
explicitly in the commentary that bond_ether_setup() is only for use on
a bond master device.  The nomenclature "bond_dev" does imply that, but
it's not explicit.

	Also, why is the call to ether_setup() from bond_setup() not
also being converted to bond_ether_setup()?

	-J

>+
> /* enslave device <slave> to bond device <master> */
> int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev,
> 		 struct netlink_ext_ack *extack)
>-- 
>2.39.2
>

---
	-Jay Vosburgh, jay.vosburgh@...onical.com