Re: [PATCH v5 10/12] ndp: Pass queue pair explicitly through NDP send path

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Jun 16, 2026 at 02:51:28PM +0200, Laurent Vivier wrote:
> Add a qpair parameter to ndp(), ndp_send(), ndp_na(),
> ndp_unsolicited_na(), ndp_ra(), and ndp_send_init_req(), forwarding
> it to tap_icmp6_send() instead of hardcoding QPAIR_DEFAULT.
> 
> ndp_timer() and fwd_neigh_table_update() have no queue pair context
> and keep using QPAIR_DEFAULT.
> 
> No functional change.
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
>  fwd.c |  2 +-
>  ndp.c | 40 ++++++++++++++++++++++++----------------
>  ndp.h |  7 ++++---
>  tap.c |  4 ++--
>  4 files changed, 31 insertions(+), 22 deletions(-)
> 
> diff --git a/fwd.c b/fwd.c
> index 0d0e265b7dc0..1bfe024ada26 100644
> --- a/fwd.c
> +++ b/fwd.c
> @@ -147,7 +147,7 @@ void fwd_neigh_table_update(const struct ctx *c, const union inany_addr *addr,
>  	if (inany_v4(addr))
>  		arp_announce(c, QPAIR_DEFAULT, inany_v4(addr), e->mac);
>  	else
> -		ndp_unsolicited_na(c, &addr->a6);
> +		ndp_unsolicited_na(c, QPAIR_DEFAULT, &addr->a6);
>  }
>  
>  /**
> diff --git a/ndp.c b/ndp.c
> index 6269cb38d93f..00d1751ba100 100644
> --- a/ndp.c
> +++ b/ndp.c
> @@ -175,26 +175,28 @@ struct ndp_ns {
>  /**
>   * ndp_send() - Send an NDP message
>   * @c:		Execution context
> + * @qpair:	Queue pair on which to send the message
>   * @dst:	IPv6 address to send the message to
>   * @buf:	ICMPv6 header + message payload
>   * @l4len:	Length of message, including ICMPv6 header
>   */
> -static void ndp_send(const struct ctx *c, const struct in6_addr *dst,
> -		     const void *buf, size_t l4len)
> +static void ndp_send(const struct ctx *c, unsigned int qpair,
> +		     const struct in6_addr *dst, const void *buf, size_t l4len)
>  {
>  	const struct in6_addr *src = &c->ip6.our_tap_ll;
>  
> -	tap_icmp6_send(c, QPAIR_DEFAULT, src, dst, buf, c->our_tap_mac, l4len);
> +	tap_icmp6_send(c, qpair, src, dst, buf, c->our_tap_mac, l4len);
>  }
>  
>  /**
>   * ndp_na() - Send an NDP Neighbour Advertisement (NA) message
>   * @c:		Execution context
> + * @qpair:	Queue pair on which to send the NA
>   * @dst:	IPv6 address to send the NA to
>   * @addr:	IPv6 address to advertise
>   */
> -static void ndp_na(const struct ctx *c, const struct in6_addr *dst,
> -	    const struct in6_addr *addr)
> +static void ndp_na(const struct ctx *c, unsigned int qpair,
> +		   const struct in6_addr *dst, const struct in6_addr *addr)
>  {
>  	union inany_addr tgt;
>  	struct ndp_na na = {
> @@ -217,26 +219,30 @@ static void ndp_na(const struct ctx *c, const struct in6_addr *dst,
>  	inany_from_af(&tgt, AF_INET6, addr);
>  	fwd_neigh_mac_get(c, &tgt, na.target_l2_addr.mac);
>  
> -	ndp_send(c, dst, &na, sizeof(na));
> +	ndp_send(c, qpair, dst, &na, sizeof(na));
>  }
>  
>  /**
>   * ndp_unsolicited_na() - Send unsolicited NA
>   * @c:         Execution context
> + * @qpair:     Queue pair on which to send the NA
>   * @addr:      IPv6 address to advertise
>   */
> -void ndp_unsolicited_na(const struct ctx *c, const struct in6_addr *addr)
> +void ndp_unsolicited_na(const struct ctx *c, unsigned int qpair,
> +			const struct in6_addr *addr)

Since this is unsolicited, how would the caller have a better idea of
the right qpair than we could here?

>  {
>  	if (tap_is_ready(c))
> -		ndp_na(c, &in6addr_ll_all_nodes, addr);
> +		ndp_na(c, qpair, &in6addr_ll_all_nodes, addr);
>  }
>  
>  /**
>   * ndp_ra() - Send an NDP Router Advertisement (RA) message
>   * @c:		Execution context
> + * @qpair:	Queue pair on which to send the RA
>   * @dst:	IPv6 address to send the RA to
>   */
> -static void ndp_ra(const struct ctx *c, const struct in6_addr *dst)
> +static void ndp_ra(const struct ctx *c, unsigned int qpair,
> +		   const struct in6_addr *dst)
>  {
>  	struct ndp_ra ra = {
>  		.ih = {
> @@ -344,18 +350,19 @@ static void ndp_ra(const struct ctx *c, const struct in6_addr *dst)
>  	memcpy(&ra.source_ll.mac, c->our_tap_mac, ETH_ALEN);
>  
>  	/* NOLINTNEXTLINE(clang-analyzer-security.PointerSub) */
> -	ndp_send(c, dst, &ra, ptr - (unsigned char *)&ra);
> +	ndp_send(c, qpair, dst, &ra, ptr - (unsigned char *)&ra);
>  }
>  
>  /**
>   * ndp() - Check for NDP solicitations, reply as needed
>   * @c:		Execution context
> + * @qpair:	Queue pair on which to send replies
>   * @saddr:	Source IPv6 address
>   * @data:	Single packet with ICMPv6 header
>   *
>   * Return: 0 if not handled here, 1 if handled, -1 on failure
>   */
> -int ndp(const struct ctx *c, const struct in6_addr *saddr,
> +int ndp(const struct ctx *c, unsigned int qpair, const struct in6_addr *saddr,
>  	struct iov_tail *data)
>  {
>  	struct icmp6hdr ih_storage;
> @@ -384,13 +391,13 @@ int ndp(const struct ctx *c, const struct in6_addr *saddr,
>  
>  		info("NDP: received NS, sending NA");
>  
> -		ndp_na(c, saddr, &ns->target_addr);
> +		ndp_na(c, qpair, saddr, &ns->target_addr);
>  	} else if (ih->icmp6_type == RS) {
>  		if (c->no_ra)
>  			return 1;
>  
>  		info("NDP: received RS, sending RA");
> -		ndp_ra(c, saddr);
> +		ndp_ra(c, qpair, saddr);
>  	}
>  
>  	return 1;
> @@ -448,7 +455,7 @@ void ndp_timer(const struct ctx *c, const struct timespec *now)
>  
>  	info("NDP: sending unsolicited RA, next in %llds", (long long)interval);
>  
> -	ndp_ra(c, &in6addr_ll_all_nodes);
> +	ndp_ra(c, QPAIR_DEFAULT, &in6addr_ll_all_nodes);
>  
>  first:
>  	next_ra = now->tv_sec + interval;
> @@ -457,8 +464,9 @@ first:
>  /**
>   * ndp_send_init_req() - Send initial NDP NS to retrieve guest MAC address
>   * @c:		Execution context
> + * @qpair:	Queue pair on which to send the request
>   */
> -void ndp_send_init_req(const struct ctx *c)
> +void ndp_send_init_req(const struct ctx *c, unsigned int qpair)
>  {
>  	struct ndp_ns ns = {
>  		.ih = {
> @@ -471,5 +479,5 @@ void ndp_send_init_req(const struct ctx *c)
>  		.target_addr = c->ip6.addr
>  	};
>  	debug("Sending initial NDP NS request for guest MAC address");
> -	ndp_send(c, &c->ip6.addr, &ns, sizeof(ns));
> +	ndp_send(c, qpair, &c->ip6.addr, &ns, sizeof(ns));
>  }
> diff --git a/ndp.h b/ndp.h
> index 56b756d8400b..8c168fc199fe 100644
> --- a/ndp.h
> +++ b/ndp.h
> @@ -8,10 +8,11 @@
>  
>  struct icmp6hdr;
>  
> -int ndp(const struct ctx *c, const struct in6_addr *saddr,
> +int ndp(const struct ctx *c, unsigned int qpair, const struct in6_addr *saddr,
>  	struct iov_tail *data);
>  void ndp_timer(const struct ctx *c, const struct timespec *now);
> -void ndp_send_init_req(const struct ctx *c);
> -void ndp_unsolicited_na(const struct ctx *c, const struct in6_addr *addr);
> +void ndp_send_init_req(const struct ctx *c, unsigned int qpair);
> +void ndp_unsolicited_na(const struct ctx *c, unsigned int qpair,
> +			const struct in6_addr *addr);
>  
>  #endif /* NDP_H */
> diff --git a/tap.c b/tap.c
> index de1e5269526c..5e9c7a1701bf 100644
> --- a/tap.c
> +++ b/tap.c
> @@ -1030,7 +1030,7 @@ resume:
>  				continue;
>  
>  			ndp_data = data;
> -			if (ndp(c, saddr, &ndp_data))
> +			if (ndp(c, qpair, saddr, &ndp_data))
>  				continue;
>  
>  			tap_packet_debug(NULL, ip6h, NULL, proto, NULL, 1);
> @@ -1470,7 +1470,7 @@ static void tap_start_connection(const struct ctx *c, unsigned int qpair)
>  	if (c->ifi4)
>  		arp_send_init_req(c, qpair);
>  	if (c->ifi6 && !c->no_ndp)
> -		ndp_send_init_req(c);
> +		ndp_send_init_req(c, qpair);
>  }
>  
>  /**
> -- 
> 2.54.0
> 

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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