Re: [PATCH v3 00/20] Draft, incomplete series introducing state migration

On Sat, Feb 01, 2025 at 08:45:18AM +0100, Stefano Brivio wrote:

On Fri, 31 Jan 2025 20:39:33 +0100 Stefano Brivio wrote:

...

What clearly needs changes:

Maybe something less elegant but actually functional like:

--- static int migrate_data_v1(int fd, struct ctx *c, bool target) { struct iovec context[] { /* All these need to be network endian */ c->hash_secret, sizeof(c->hash_secret), c->ipv4.addr_seen, sizeof(c->ipv4.addr_seen), c->ipv6.addr_seen, sizeof(c->ipv6.addr_seen), c->ipv6.addr_ll_seen, sizeof(c->ipv6.addr_ll_seen), /* Leave NDP's next_ra alone, start from 0 */ &log_written /* Drop static */ sizeof(log_written), }; int rc;

if (target) rc = read_remainder(fd, context, ARRAY_SIZE(context), 0); else rc = write_remainder(fd, context, ARRAY_SIZE(context), 0);

if (rc) return errno;

if (target) return flow_migrate_data_target_v1(fd, c); return flow_migrate_data_source_v1(fd, c); } ---

and:

--- struct tcp_flow_transfer_v1 { struct flow_common f;

uint8_t retrans;

uint16_t ws_from_tap; /* All BE */ uint16_t ws_to_tap; uint16_t tap_mss;

... } __attribute__((packed));

union flow_transfer_v1 { struct tcp_flow_transfer_v1 tcp; ... };

int flow_migrate_data_source_v1(int fd, struct ctx *c) { for_each_active_flow(flowtab) { union flow_transfer_v1 d;

switch (flow->f.type) { case FLOW_TCP: d.tcp.f = flow->f; d.tcp.retrans = flow->tcp.retrans; d.tcp.ws_from_tap = htons(d.tcp.ws_from_tap); ...;

/* Fetch window stuff, socket must be in repair mode */

send(...); }

int flow_migrate_data_target_v1(int fd, struct ctx *c) { ... }

And I'm not sure about "[PATCH 0/2] Fancier version handling for migration": perhaps we could switch to something radically easier from the beginning. I mean, as we have to drop the declarative approach altogether, at least let's minimise LoCs...

Yeah, I think I have a better idea that kind of covers both of these. Patches shortly, I hope. -- 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