netdev - Re: [PATCH v2 net-next] Enhanced skb_mpls_pop to update ethertype of the packet in all the cases when an ethernet header is present is the packet.

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Date:   Mon, 25 Nov 2019 16:32:34 +0530
From:   Martin Varghese <martinvarghesenokia@...il.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     netdev@...r.kernel.org, pshelar@....org, davem@...emloft.net,
        jhs@...atatu.com, xiyou.wangcong@...il.com, jiri@...nulli.us,
        martin.varghese@...ia.com
Subject: Re: [PATCH v2 net-next] Enhanced skb_mpls_pop to update ethertype of
 the packet in all the cases when an ethernet header is present is the
 packet.

On Sun, Nov 24, 2019 at 07:10:08PM -0800, Jakub Kicinski wrote:
> On Sat, 23 Nov 2019 16:04:59 +0530, Martin Varghese wrote:
> > From: Martin Varghese <martin.varghese@...ia.com>
> > 
> > The skb_mpls_pop was not updating ethertype of an ethernet packet if the
> > packet was originally received from a non ARPHRD_ETHER device.
> > 
> > In the below OVS data path flow, since the device corresponding to port 7
> > is an l3 device (ARPHRD_NONE) the skb_mpls_pop function does not update
> > the ethertype of the packet even though the previous push_eth action had
> > added an ethernet header to the packet.
> > 
> > recirc_id(0),in_port(7),eth_type(0x8847),
> > mpls(label=12/0xfffff,tc=0/0,ttl=0/0x0,bos=1/1),
> > actions:push_eth(src=00:00:00:00:00:00,dst=00:00:00:00:00:00),
> > pop_mpls(eth_type=0x800),4
> > 
> > Signed-off-by: Martin Varghese <martin.varghese@...ia.com>
> 
> So this fixes all the way back to commit ed246cee09b9 ("net: core: move
> pop MPLS functionality from OvS to core helper")? Please add a Fixes: tag.
> 
> > Changes in v2:
> >     - check for dev type removed while updating ethertype
> >       in function skb_mpls_pop.
> >     - key->mac_proto is checked in function pop_mpls to pass
> >       ethernt flag to skb_mpls_pop.
> >     - dev type is checked in function tcf_mpls_act to pass
> >       ethernet flag to skb_mpls_pop.
> 
> nit: changelog can be kept in the commit message for netdev patches
>
Multiple versions are mostly due to coding error.do you insist to keep
the change log in commit message ?
 
> > diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> > index 867e61d..988eefb 100644
> > --- a/net/core/skbuff.c
> > +++ b/net/core/skbuff.c
> > @@ -5529,12 +5529,13 @@ int skb_mpls_push(struct sk_buff *skb, __be32 mpls_lse, __be16 mpls_proto,
> >   * @skb: buffer
> >   * @next_proto: ethertype of header after popped MPLS header
> >   * @mac_len: length of the MAC header
> > - *
> > + * @ethernet: flag to indicate if ethernet header is present in packet
> 
> Please don't remove the empty line between params and function
> description.
> 
> >   * Expects skb->data at mac header.
> >   *
> >   * Returns 0 on success, -errno otherwise.
> >   */
> > -int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len)
> > +int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len,
> > +		 bool ethernet)
> >  {
> >  	int err;
> >  
> 
> > diff --git a/net/sched/act_mpls.c b/net/sched/act_mpls.c
> > index 4d8c822..f919f95 100644
> > --- a/net/sched/act_mpls.c
> > +++ b/net/sched/act_mpls.c
> > @@ -13,6 +13,7 @@
> >  #include <net/pkt_sched.h>
> >  #include <net/pkt_cls.h>
> >  #include <net/tc_act/tc_mpls.h>
> > +#include <linux/if_arp.h>
> 
> Please retain the alphabetical order of includes.
> 
> >  static unsigned int mpls_net_id;
> >  static struct tc_action_ops act_mpls_ops;
> > @@ -76,7 +77,8 @@ static int tcf_mpls_act(struct sk_buff *skb, const struct tc_action *a,
> >  
> >  	switch (p->tcfm_action) {
> >  	case TCA_MPLS_ACT_POP:
> > -		if (skb_mpls_pop(skb, p->tcfm_proto, mac_len))
> > +		if (skb_mpls_pop(skb, p->tcfm_proto, mac_len,
> > +				 (skb->dev && skb->dev->type == ARPHRD_ETHER)))
> 
> Parenthesis unnecessary
> 
> >  			goto drop;
> >  		break;
> >  	case TCA_MPLS_ACT_PUSH:
> 
Thanks for reviewing the patch.