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KRT: Improve syncer code to avoid using temporary data in rtable

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The old code stored route verdicts and temporary routes directly in
rtable. The new code do not store received routes (it immediately
compares them with exported routes and resolves conflicts) and uses
internal bitmap to keep track of which routes were received and which
needs to be reinstalled.

By not putting 'invalid' temporary routes to rtable, we keep rtable
in consistent state, therefore scan no longer needs to be atomic
operation and could be splitted to multiple events.
This commit is contained in:
Ondrej Zajicek (work) 2020-01-07 18:35:03 +01:00
parent ef8c45749c
commit 7d767c5a3d
5 changed files with 77 additions and 112 deletions
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1
nest/route.h
View file

@ -37,7 +37,6 @@ struct cli;
struct fib_node {
struct fib_node *next; /* Next in hash chain */
struct fib_iterator *readers; /* List of readers of this node */
byte flags; /* User-defined, will be removed */
net_addr addr[0];
};

1
nest/rt-fib.c
View file

@ -327,7 +327,6 @@ fib_get(struct fib *f, const net_addr *a)
struct fib_node *e = fib_user_to_node(f, b);
e->readers = NULL;
e->flags = 0;
fib_insert(f, a, e);
memset(b, 0, f->node_offset);

2
nest/rt-table.c
View file

@ -1687,7 +1687,7 @@ rte_dump(rte *e)
{
net *n = e->net;
debug("%-1N ", n->n.addr);
debug("KF=%02x PF=%02x pref=%d ", n->n.flags, e->pflags, e->pref);
debug("PF=%02x pref=%d ", e->pflags, e->pref);
rta_dump(e->attrs);
if (e->attrs->src->proto->proto->dump_attrs)
e->attrs->src->proto->proto->dump_attrs(e);

155
sysdep/unix/krt.c
View file

@ -625,19 +625,17 @@ krt_same_dest(rte *k, rte *e)
void
krt_got_route(struct krt_proto *p, rte *e)
{
net *net = e->net;
int verdict;
rte *new = NULL, *rt_free = NULL;
net *n = e->net;
#ifdef KRT_ALLOW_LEARN
switch (e->u.krt.src)
{
case KRT_SRC_KERNEL:
verdict = KRF_IGNORE;
goto sentenced;
goto ignore;
case KRT_SRC_REDIRECT:
verdict = KRF_DELETE;
goto sentenced;
goto delete;
case KRT_SRC_ALIEN:
if (KRT_CF->learn)
@ -652,58 +650,68 @@ krt_got_route(struct krt_proto *p, rte *e)
#endif
/* The rest is for KRT_SRC_BIRD (or KRT_SRC_UNKNOWN) */
if (net->n.flags & KRF_VERDICT_MASK)
{
/* Route to this destination was already seen. Strange, but it happens... */
krt_trace_in(p, e, "already seen");
rte_free(e);
return;
}
if (!p->ready)
{
/* We wait for the initial feed to have correct installed state */
verdict = KRF_IGNORE;
goto sentenced;
}
if (!p->ready)
goto ignore;
if (krt_is_installed(p, net))
{
rte *new, *rt_free;
if (!krt_is_installed(p, n))
goto delete;
new = krt_export_net(p, net, &rt_free);
new = krt_export_net(p, n, &rt_free);
/* Rejected by filters */
if (!new)
goto delete;
/* Route to this destination was already seen. Strange, but it happens... */
if (bmap_test(&p->seen_map, new->id))
goto aseen;
/* Mark route as seen */
bmap_set(&p->seen_map, new->id);
/* TODO: There also may be changes in route eattrs, we ignore that for now. */
if (!bmap_test(&p->sync_map, new->id) || !krt_same_dest(e, new))
goto update;
if (!new)
verdict = KRF_DELETE;
else if (!bmap_test(&p->sync_map, new->id) || !krt_same_dest(e, new))
verdict = KRF_UPDATE;
else
verdict = KRF_SEEN;
goto seen;
seen:
krt_trace_in(p, e, "seen");
goto done;
aseen:
krt_trace_in(p, e, "already seen");
goto done;
ignore:
krt_trace_in(p, e, "ignored");
goto done;
update:
krt_trace_in(p, new, "updating");
krt_replace_rte(p, n, new, e);
goto done;
delete:
krt_trace_in(p, e, "deleting");
krt_replace_rte(p, n, NULL, e);
goto done;
done:
rte_free(e);
if (rt_free)
rte_free(rt_free);
lp_flush(krt_filter_lp);
}
else
verdict = KRF_DELETE;
sentenced:
krt_trace_in(p, e, ((char *[]) { "?", "seen", "will be updated", "will be removed", "ignored" }) [verdict]);
net->n.flags = (net->n.flags & ~KRF_VERDICT_MASK) | verdict;
if (verdict == KRF_UPDATE || verdict == KRF_DELETE)
static void
krt_init_scan(struct krt_proto *p)
{
/* Get a cached copy of attributes and temporarily link the route */
rta *a = e->attrs;
a->source = RTS_DUMMY;
e->attrs = rta_lookup(a);
e->next = net->routes;
net->routes = e;
}
else
rte_free(e);
bmap_reset(&p->seen_map, 1024);
}
static void
@ -714,57 +722,22 @@ krt_prune(struct krt_proto *p)
KRT_TRACE(p, D_EVENTS, "Pruning table %s", t->name);
FIB_WALK(&t->fib, net, n)
{
int verdict = n->n.flags & KRF_VERDICT_MASK;
rte *new, *old, *rt_free = NULL;
if (verdict == KRF_UPDATE || verdict == KRF_DELETE)
if (p->ready && krt_is_installed(p, n) && !bmap_test(&p->seen_map, n->routes->id))
{
/* Get a dummy route from krt_got_route() */
old = n->routes;
n->routes = old->next;
}
else
old = NULL;
rte *rt_free = NULL;
rte *new = krt_export_net(p, n, &rt_free);
if (verdict == KRF_CREATE || verdict == KRF_UPDATE)
if (new)
{
/* We have to run export filter to get proper 'new' route */
new = krt_export_net(p, n, &rt_free);
if (!new)
verdict = (verdict == KRF_CREATE) ? KRF_IGNORE : KRF_DELETE;
}
else
new = NULL;
switch (verdict)
{
case KRF_CREATE:
krt_trace_in(p, new, "reinstalling");
krt_trace_in(p, new, "installing");
krt_replace_rte(p, n, new, NULL);
break;
case KRF_SEEN:
case KRF_IGNORE:
/* Nothing happens */
break;
case KRF_UPDATE:
krt_trace_in(p, new, "updating");
krt_replace_rte(p, n, new, old);
break;
case KRF_DELETE:
krt_trace_in(p, old, "deleting");
krt_replace_rte(p, n, NULL, old);
break;
default:
bug("krt_prune: invalid route status");
}
if (old)
rte_free(old);
if (rt_free)
rte_free(rt_free);
lp_flush(krt_filter_lp);
n->n.flags &= ~KRF_VERDICT_MASK;
}
}
FIB_WALK_END;
@ -823,6 +796,7 @@ static void
krt_scan(timer *t UNUSED)
{
struct krt_proto *p;
node *n;
kif_force_scan();
@ -830,15 +804,14 @@ krt_scan(timer *t UNUSED)
p = SKIP_BACK(struct krt_proto, krt_node, HEAD(krt_proto_list));
KRT_TRACE(p, D_EVENTS, "Scanning routing table");
WALK_LIST2(p, n, krt_proto_list, krt_node)
krt_init_scan(p);
krt_do_scan(NULL);
void *q;
WALK_LIST(q, krt_proto_list)
{
p = SKIP_BACK(struct krt_proto, krt_node, q);
WALK_LIST2(p, n, krt_proto_list, krt_node)
krt_prune(p);
}
}
static void
krt_scan_timer_start(struct krt_proto *p)
@ -879,6 +852,7 @@ krt_scan(timer *t)
kif_force_scan();
KRT_TRACE(p, D_EVENTS, "Scanning routing table");
krt_init_scan(p);
krt_do_scan(p);
krt_prune(p);
}
@ -1095,6 +1069,7 @@ krt_start(struct proto *P)
}
bmap_init(&p->sync_map, p->p.pool, 1024);
bmap_init(&p->seen_map, p->p.pool, 1024);
add_tail(&krt_proto_list, &p->krt_node);
#ifdef KRT_ALLOW_LEARN

10
sysdep/unix/krt.h
View file

@ -19,15 +19,6 @@ struct kif_proto;
#include "sysdep/config.h"
#include CONFIG_INCLUDE_KRTSYS_H
/* Flags stored in net->n.flags, rest are in nest/route.h */
#define KRF_VERDICT_MASK 0x0f
#define KRF_CREATE 0 /* Not seen in kernel table */
#define KRF_SEEN 1 /* Seen in kernel table during last scan */
#define KRF_UPDATE 2 /* Need to update this entry */
#define KRF_DELETE 3 /* Should be deleted */
#define KRF_IGNORE 4 /* To be ignored */
#define KRT_DEFAULT_ECMP_LIMIT 16
#define EA_KRT_SOURCE EA_CODE(PROTOCOL_KERNEL, 0)
@ -66,6 +57,7 @@ struct krt_proto {
#endif
struct bmap sync_map; /* Keeps track which exported routes were successfully written to kernel */
struct bmap seen_map; /* Routes seen during last periodic scan */
node krt_node; /* Node in krt_proto_list */
byte af; /* Kernel address family (AF_*) */
byte ready; /* Initial feed has been finished */