Re: [PATCH v3 06/11] pasta: Extract pasta_ns_conf_ip4/6() to reduce nesting

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

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On Fri, Jan 30, 2026 at 04:44:42PM -0500, Jon Maloy wrote:
> Extract the IPv4 and IPv6 namespace configuration code from
> pasta_ns_conf() into separate static functions. This reduces
> indentation depth and prepares for adding multi-address support.
> 
> No functional change.

This seems fine in isolation, but I think it moves in the wrong
direction in context.  With the unified address array, we want to step
through and set all the addresses in a single pass - this kind of
works against that.

> 
> Signed-off-by: Jon Maloy <jmaloy@redhat.com>
> ---
>  pasta.c | 182 ++++++++++++++++++++++++++++++--------------------------
>  1 file changed, 96 insertions(+), 86 deletions(-)
> 
> diff --git a/pasta.c b/pasta.c
> index 08f35f4..de0ba14 100644
> --- a/pasta.c
> +++ b/pasta.c
> @@ -303,6 +303,98 @@ void pasta_start_ns(struct ctx *c, uid_t uid, gid_t gid,
>  		die_perror("Failed to join network namespace");
>  }
>  
> +/**
> + * pasta_ns_conf_ip4() - Configure IPv4 in namespace
> + * @c:		Execution context
> + */
> +static void pasta_ns_conf_ip4(struct ctx *c)
> +{
> +	int rc = 0;
> +
> +	if (c->ip4.no_copy_addrs) {
> +		struct inany_addr_entry *e = first_v4(c);
> +
> +		rc = nl_addr_set(nl_sock_ns, c->pasta_ifi, AF_INET,
> +				 inany_v4(&e->addr), e->prefix_len - 96);
> +	} else {
> +		rc = nl_addr_dup(nl_sock, c->ifi4,
> +				 nl_sock_ns, c->pasta_ifi, AF_INET);
> +	}
> +
> +	if (rc < 0) {
> +		die("Couldn't set IPv4 address(es) in namespace: %s",
> +		    strerror_(-rc));
> +	}
> +
> +	if (c->ip4.no_copy_routes) {
> +		rc = nl_route_set_def(nl_sock_ns, c->pasta_ifi,
> +				      AF_INET, &c->ip4.guest_gw);
> +	} else {
> +		rc = nl_route_dup(nl_sock, c->ifi4, nl_sock_ns,
> +				  c->pasta_ifi, AF_INET);
> +	}
> +
> +	if (rc < 0) {
> +		die("Couldn't set IPv4 route(s) in guest: %s",
> +		    strerror_(-rc));
> +	}
> +}
> +
> +/**
> + * pasta_ns_conf_ip6() - Configure IPv6 in namespace
> + * @c:		Execution context
> + */
> +static void pasta_ns_conf_ip6(struct ctx *c)
> +{
> +	struct inany_addr_entry *e;
> +	int rc = 0;
> +
> +	rc = nl_addr_get_ll(nl_sock_ns, c->pasta_ifi, &c->ip6.addr_ll_seen);
> +	if (rc < 0) {
> +		warn("Can't get LL address from namespace: %s",
> +		     strerror_(-rc));
> +	}
> +
> +	rc = nl_addr_set_ll_nodad(nl_sock_ns, c->pasta_ifi);
> +	if (rc < 0) {
> +		warn("Can't set nodad for LL in namespace: %s",
> +		     strerror_(-rc));
> +	}
> +
> +	/* We dodged DAD: re-enable neighbour solicitations */
> +	nl_link_set_flags(nl_sock_ns, c->pasta_ifi, 0, IFF_NOARP);
> +
> +	if (c->ip6.no_copy_addrs) {
> +		e = first_v6(c);
> +
> +		if (e && !IN6_IS_ADDR_UNSPECIFIED(&e->addr.a6)) {
> +			rc = nl_addr_set(nl_sock_ns, c->pasta_ifi,
> +					 AF_INET6, &e->addr.a6, 64);
> +		}
> +	} else {
> +		rc = nl_addr_dup(nl_sock, c->ifi6,
> +				 nl_sock_ns, c->pasta_ifi, AF_INET6);
> +	}
> +
> +	if (rc < 0) {
> +		die("Couldn't set IPv6 address(es) in namespace: %s",
> +		    strerror_(-rc));
> +	}
> +
> +	if (c->ip6.no_copy_routes) {
> +		rc = nl_route_set_def(nl_sock_ns, c->pasta_ifi,
> +				      AF_INET6, &c->ip6.guest_gw);
> +	} else {
> +		rc = nl_route_dup(nl_sock, c->ifi6,
> +				  nl_sock_ns, c->pasta_ifi, AF_INET6);
> +	}
> +
> +	if (rc < 0) {
> +		die("Couldn't set IPv6 route(s) in guest: %s",
> +		    strerror_(-rc));
> +	}
> +}
> +
>  /**
>   * pasta_ns_conf() - Set up loopback and tap interfaces in namespace as needed
>   * @c:		Execution context
> @@ -336,93 +428,11 @@ void pasta_ns_conf(struct ctx *c)
>  
>  		nl_link_set_flags(nl_sock_ns, c->pasta_ifi, flags, flags);
>  
> -		if (c->ifi4) {
> -			if (c->ip4.no_copy_addrs) {
> -				struct inany_addr_entry *e = first_v4(c);
> -
> -				rc = nl_addr_set(nl_sock_ns, c->pasta_ifi,
> -						 AF_INET,
> -						 inany_v4(&e->addr),
> -						 e->prefix_len);
> -			} else {
> -				rc = nl_addr_dup(nl_sock, c->ifi4,
> -						 nl_sock_ns, c->pasta_ifi,
> -						 AF_INET);
> -			}
> -
> -			if (rc < 0) {
> -				die("Couldn't set IPv4 address(es) in namespace: %s",
> -				    strerror_(-rc));
> -			}
> -
> -			if (c->ip4.no_copy_routes) {
> -				rc = nl_route_set_def(nl_sock_ns, c->pasta_ifi,
> -						      AF_INET,
> -						      &c->ip4.guest_gw);
> -			} else {
> -				rc = nl_route_dup(nl_sock, c->ifi4, nl_sock_ns,
> -						  c->pasta_ifi, AF_INET);
> -			}
> -
> -			if (rc < 0) {
> -				die("Couldn't set IPv4 route(s) in guest: %s",
> -				    strerror_(-rc));
> -			}
> -		}
> +		if (c->ifi4)
> +			pasta_ns_conf_ip4(c);
>  
> -		if (c->ifi6) {
> -			rc = nl_addr_get_ll(nl_sock_ns, c->pasta_ifi,
> -					    &c->ip6.addr_ll_seen);
> -			if (rc < 0) {
> -				warn("Can't get LL address from namespace: %s",
> -				    strerror_(-rc));
> -			}
> -
> -			rc = nl_addr_set_ll_nodad(nl_sock_ns, c->pasta_ifi);
> -			if (rc < 0) {
> -				warn("Can't set nodad for LL in namespace: %s",
> -				    strerror_(-rc));
> -			}
> -
> -			/* We dodged DAD: re-enable neighbour solicitations */
> -			nl_link_set_flags(nl_sock_ns, c->pasta_ifi,
> -					  0, IFF_NOARP);
> -
> -			if (c->ip6.no_copy_addrs) {
> -				struct inany_addr_entry *e = first_v6(c);
> -
> -				if (e && !IN6_IS_ADDR_UNSPECIFIED(&e->addr.a6)) {
> -					rc = nl_addr_set(nl_sock_ns,
> -							 c->pasta_ifi,
> -							 AF_INET6,
> -							 &e->addr.a6, 64);
> -				}
> -			} else {
> -				rc = nl_addr_dup(nl_sock, c->ifi6,
> -						 nl_sock_ns, c->pasta_ifi,
> -						 AF_INET6);
> -			}
> -
> -			if (rc < 0) {
> -				die("Couldn't set IPv6 address(es) in namespace: %s",
> -				    strerror_(-rc));
> -			}
> -
> -			if (c->ip6.no_copy_routes) {
> -				rc = nl_route_set_def(nl_sock_ns, c->pasta_ifi,
> -						      AF_INET6,
> -						      &c->ip6.guest_gw);
> -			} else {
> -				rc = nl_route_dup(nl_sock, c->ifi6,
> -						  nl_sock_ns, c->pasta_ifi,
> -						  AF_INET6);
> -			}
> -
> -			if (rc < 0) {
> -				die("Couldn't set IPv6 route(s) in guest: %s",
> -				    strerror_(-rc));
> -			}
> -		}
> +		if (c->ifi6)
> +			pasta_ns_conf_ip6(c);
>  	}
>  
>  	proto_update_l2_buf(c->guest_mac);
> -- 
> 2.52.0
> 

-- 
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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