From: Vitaliy Makkoveev <mvs@openbsd.org>
Subject: Re: preserve mbuf flowid in if_input_local
To: David Gwynne <david@gwynne.id.au>
Cc: tech@openbsd.org, bluhm@openbsd.org
Date: Wed, 7 May 2025 11:30:28 +0300

On Wed, May 07, 2025 at 11:03:12AM +1000, David Gwynne wrote:
> we're not changing the content of the packet, so the flowid is still
> valid. m_resethdr() clears the field, so we need to preserve it ourselves
> though.
> 
> ok?
> 

ok mvs

> Index: if.c
> ===================================================================
> RCS file: /cvs/src/sys/net/if.c,v
> diff -u -p -r1.731 if.c
> --- if.c	1 May 2025 11:19:46 -0000	1.731
> +++ if.c	7 May 2025 01:01:46 -0000
> @@ -785,6 +785,7 @@ if_input_local(struct ifnet *ifp, struct
>  {
>  	int keepflags, keepcksum;
>  	uint16_t keepmss;
> +	uint16_t keepflowid;
>  
>  #if NBPFILTER > 0
>  	/*
> @@ -809,12 +810,14 @@ if_input_local(struct ifnet *ifp, struct
>  	 */
>  	keepcksum = m->m_pkthdr.csum_flags & (M_IPV4_CSUM_OUT |
>  	    M_TCP_CSUM_OUT | M_UDP_CSUM_OUT | M_ICMP_CSUM_OUT |
> -	    M_TCP_TSO);
> +	    M_TCP_TSO | M_FLOWID);
>  	keepmss = m->m_pkthdr.ph_mss;
> +	keepflowid = m->m_pkthdr.ph_flowid;
>  	m_resethdr(m);
>  	m->m_flags |= M_LOOP | keepflags;
>  	m->m_pkthdr.csum_flags = keepcksum;
>  	m->m_pkthdr.ph_mss = keepmss;
> +	m->m_pkthdr.ph_flowid = keepflowid;
>  	m->m_pkthdr.ph_ifidx = ifp->if_index;
>  	m->m_pkthdr.ph_rtableid = ifp->if_rdomain;
>  
>