Re: [PATCH v14 02/10] passt: add no_map_gw flag to struct ctx

On Tue, 14 Oct 2025 22:55:13 -0400 Jon Maloy wrote:

Later in this series we will introduce a new initialization function which needs access to the 'no_map_gw' flag. This flag is currently a local variable inside the conf() call, where it is too early to call the new function. The new function needs both ctx->hash_secret and a valid ctx->fd_tap to be set, neither of which are initialized at that point.

We therefore add the 'no_map_gw' flag to struct ctx, so it can be carried along and used by later functions.

Signed-off-by: Jon Maloy Reviewed-by: David Gibson

--- v14: Fixed typo in commit log --- conf.c | 10 +++++----- passt.h | 1 + 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/conf.c b/conf.c index 66b9e63..6143b54 100644 --- a/conf.c +++ b/conf.c @@ -1410,7 +1410,7 @@ fail: */ void conf(struct ctx *c, int argc, char **argv) { - int netns_only = 0, no_map_gw = 0; + int netns_only = 0; const struct option options[] = { {"debug", no_argument, NULL, 'd' }, {"quiet", no_argument, NULL, 'q' }, @@ -1442,7 +1442,7 @@ void conf(struct ctx *c, int argc, char **argv) {"no-ra", no_argument, &c->no_ra, 1 }, {"no-splice", no_argument, &c->no_splice, 1 }, {"freebind", no_argument, &c->freebind, 1 }, - {"no-map-gw", no_argument, &no_map_gw, 1 }, + {"no-map-gw", no_argument, &c->no_map_gw, 1 }, {"ipv4-only", no_argument, NULL, '4' }, {"ipv6-only", no_argument, NULL, '6' }, {"one-off", no_argument, NULL, '1' }, @@ -1656,7 +1656,7 @@ void conf(struct ctx *c, int argc, char **argv) break; case 21: conf_nat(optarg, &c->ip4.map_host_loopback, - &c->ip6.map_host_loopback, &no_map_gw); + &c->ip6.map_host_loopback, &c->no_map_gw);

This is by the way what causes the pre-existing issue you reported in fee75072-42c9-4bc6-959d-9641f0b27ebd@redhat.com as we should process the no_map_gw in a separate argument parsing loop first, and only then we can call conf_nat().

break; case 22: conf_nat(optarg, &c->ip4.map_guest_addr, @@ -2005,11 +2005,11 @@ void conf(struct ctx *c, int argc, char **argv) } }

- if (c->ifi4 && !no_map_gw && + if (c->ifi4 && !c->no_map_gw && IN4_IS_ADDR_UNSPECIFIED(&c->ip4.map_host_loopback)) c->ip4.map_host_loopback = c->ip4.guest_gw;

- if (c->ifi6 && !no_map_gw && + if (c->ifi6 && !c->no_map_gw && IN6_IS_ADDR_UNSPECIFIED(&c->ip6.map_host_loopback)) c->ip6.map_host_loopback = c->ip6.guest_gw;

diff --git a/passt.h b/passt.h index 0075eb4..830bc36 100644 --- a/passt.h +++ b/passt.h @@ -310,6 +310,7 @@ struct ctx { int no_ndp; int no_ra; int no_splice; + int no_map_gw;

This is now undocumented. See 935bd81936cf ("conf, fwd: Split notion of gateway/router from guest-visible host address") for the hunk you're reverting here.

int host_lo_to_ns_lo; int freebind;

-- Stefano