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Message-ID: <09f45decdd92494f9ef5abb2c5ce13f3@AcuMS.aculab.com>
Date: Fri, 21 Jul 2023 09:52:05 +0000
From: David Laight <David.Laight@...LAB.COM>
To: 'Richard Gobert' <richardbgobert@...il.com>,
"davem@...emloft.net" <davem@...emloft.net>,
"edumazet@...gle.com" <edumazet@...gle.com>,
"kuba@...nel.org" <kuba@...nel.org>,
"pabeni@...hat.com" <pabeni@...hat.com>,
"willemdebruijn.kernel@...il.com" <willemdebruijn.kernel@...il.com>,
"dsahern@...nel.org" <dsahern@...nel.org>,
"tom@...bertland.com" <tom@...bertland.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"gal@...dia.com" <gal@...dia.com>
Subject: RE: [PATCH v2 1/1] net: gro: fix misuse of CB in udp socket lookup
From: Richard Gobert
> Sent: 20 July 2023 17:26
>
> This patch fixes a misuse of IP{6}CB(skb) in GRO, while calling to
> `udp6_lib_lookup2` when handling udp tunnels. `udp6_lib_lookup2` fetch the
> device from CB. The fix changes it to fetch the device from `skb->dev`.
> l3mdev case requires special attention since it has a master and a slave
> device.
>
...
> +/* This function is the alternative to 'inet_iif' and 'inet_sdif'
> + * functions in case we can not rely on fields of IPCB.
> + *
> + * The caller must verify skb_valid_dst(skb) is false and skb->dev is initialized.
> + * The caller must hold the RCU read lock.
> + */
> +inline void udp4_get_iif_sdif(const struct sk_buff *skb, int *iif, int *sdif)
> +{
> + *iif = inet_iif(skb) ?: skb->dev->ifindex;
> + *sdif = 0;
> +
> +#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
> + if (netif_is_l3_slave(skb->dev)) {
> + struct net_device *master = netdev_master_upper_dev_get_rcu(skb->dev);
> +
> + *sdif = *iif;
> + *iif = master ? master->ifindex : 0;
> + }
> +#endif
> +}
You need to make that a 'static inline' in the .h file.
Otherwise the code generated will be horrid.
It would be much better to use the return value - say for 'iif'
then have:
{
iif = inet_iif(skb) ?: skb->dev->ifindex;
if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
if (netif_is_l3_slave(skb->dev)) {
struct net_device *master = netdev_master_upper_dev_get_rcu(skb->dev);
*sdif = iif;
return master ? master->ifindex : 0;
}
#endif
*sdif = 0;
return iif;
}
The compiler might generate that is inlined, not inlined
it is definitely better.
David
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