Converting the former BFD loop to a universal IO loop and protocol loop.

There is a simple universal IO loop, taking care of events, timers and
sockets. Primarily, one instance of a protocol should use exactly one IO
loop to do all its work, as is now done in BFD.

Contrary to previous versions, the loop is now launched and cleaned by
the nest/proto.c code, allowing for a protocol to just request its own
loop by setting the loop's lock order in config higher than the_bird.

It is not supported nor checked if any protocol changed the requested
lock order in reconfigure. No protocol should do it at all.

1 files changed, 97 insertions, 69 deletions

diff --git a/proto/bfd/bfd.c b/proto/bfd/bfd.c
index dac184c5..3964c267 100644
--- a/proto/bfd/bfd.c
+++ b/proto/bfd/bfd.c
@@ -113,8 +113,16 @@
 #define HASH_IP_EQ(a1,n1,a2,n2)	ipa_equal(a1, a2) && n1 == n2
 #define HASH_IP_FN(a,n)		ipa_hash(a) ^ u32_hash(n)
 
-static list bfd_proto_list;
-static list bfd_wait_list;
+DEFINE_DOMAIN(rtable);
+#define BFD_LOCK	LOCK_DOMAIN(rtable, bfd_global.lock)
+#define BFD_UNLOCK	UNLOCK_DOMAIN(rtable, bfd_global.lock)
+
+static struct {
+  DOMAIN(rtable) lock;
+  list wait_list;
+  list pickup_list;
+  list proto_list;
+} bfd_global;
 
 const char *bfd_state_names[] = { "AdminDown", "Down", "Init", "Up" };
 
@@ -188,7 +196,7 @@ bfd_session_update_tx_interval(struct bfd_session *s)
     return;
 
   /* Set timer relative to last tx_timer event */
-  tm_set(s->tx_timer, s->last_tx + tx_int_l);
+  tm_set_in(s->tx_timer, s->last_tx + tx_int_l, s->ifa->bfd->p.loop);
 }
 
 static void
@@ -202,7 +210,7 @@ bfd_session_update_detection_time(struct bfd_session *s, int kick)
   if (!s->last_rx)
     return;
 
-  tm_set(s->hold_timer, s->last_rx + timeout);
+  tm_set_in(s->hold_timer, s->last_rx + timeout, s->ifa->bfd->p.loop);
 }
 
 static void
@@ -226,7 +234,7 @@ bfd_session_control_tx_timer(struct bfd_session *s, int reset)
   if (reset || !tm_active(s->tx_timer))
   {
     s->last_tx = 0;
-    tm_start(s->tx_timer, 0);
+    tm_start_in(s->tx_timer, 0, s->ifa->bfd->p.loop);
   }
 
   return;
@@ -419,7 +427,7 @@ bfd_get_free_id(struct bfd_proto *p)
 static struct bfd_session *
 bfd_add_session(struct bfd_proto *p, ip_addr addr, ip_addr local, struct iface *iface, struct bfd_options *opts)
 {
-  birdloop_enter(p->loop);
+  ASSERT_DIE(birdloop_inside(p->p.loop));
 
   struct bfd_iface *ifa = bfd_get_iface(p, local, iface);
 
@@ -454,8 +462,6 @@ bfd_add_session(struct bfd_proto *p, ip_addr addr, ip_addr local, struct iface *
 
   TRACE(D_EVENTS, "Session to %I added", s->addr);
 
-  birdloop_leave(p->loop);
-
   return s;
 }
 
@@ -463,38 +469,34 @@ bfd_add_session(struct bfd_proto *p, ip_addr addr, ip_addr local, struct iface *
 static void
 bfd_open_session(struct bfd_proto *p, struct bfd_session *s, ip_addr local, struct iface *ifa)
 {
-  birdloop_enter(p->loop);
+  birdloop_enter(p->p.loop);
 
   s->opened = 1;
 
   bfd_session_control_tx_timer(s);
 
-  birdloop_leave(p->loop);
+  birdloop_leave(p->p.loop);
 }
 
 static void
 bfd_close_session(struct bfd_proto *p, struct bfd_session *s)
 {
-  birdloop_enter(p->loop);
+  birdloop_enter(p->p.loop);
 
   s->opened = 0;
 
   bfd_session_update_state(s, BFD_STATE_DOWN, BFD_DIAG_PATH_DOWN);
   bfd_session_control_tx_timer(s);
 
-  birdloop_leave(p->loop);
+  birdloop_leave(p->p.loop);
 }
 */
 
 static void
-bfd_remove_session(struct bfd_proto *p, struct bfd_session *s)
+bfd_remove_session_locked(struct bfd_proto *p, struct bfd_session *s)
 {
-  ip_addr ip = s->addr;
-
   /* Caller should ensure that request list is empty */
 
-  birdloop_enter(p->loop);
-
   /* Remove session from notify list if scheduled for notification */
   /* No need for bfd_lock_sessions(), we are already protected by birdloop_enter() */
   if (NODE_VALID(&s->n))
@@ -508,11 +510,17 @@ bfd_remove_session(struct bfd_proto *p, struct bfd_session *s)
   HASH_REMOVE(p->session_hash_id, HASH_ID, s);
   HASH_REMOVE(p->session_hash_ip, HASH_IP, s);
 
-  sl_free(p->session_slab, s);
+  TRACE(D_EVENTS, "Session to %I removed", s->addr);
 
-  TRACE(D_EVENTS, "Session to %I removed", ip);
+  sl_free(p->session_slab, s);
+}
 
-  birdloop_leave(p->loop);
+static void
+bfd_remove_session(struct bfd_proto *p, struct bfd_session *s)
+{
+  birdloop_enter(p->p.loop);
+  bfd_remove_session_locked(p, s);
+  birdloop_leave(p->p.loop);
 }
 
 static void
@@ -521,7 +529,7 @@ bfd_reconfigure_session(struct bfd_proto *p, struct bfd_session *s)
   if (EMPTY_LIST(s->request_list))
     return;
 
-  birdloop_enter(p->loop);
+  birdloop_enter(p->p.loop);
 
   struct bfd_request *req = SKIP_BACK(struct bfd_request, n, HEAD(s->request_list));
   s->cf = bfd_merge_options(s->ifa->cf, &req->opts);
@@ -534,7 +542,7 @@ bfd_reconfigure_session(struct bfd_proto *p, struct bfd_session *s)
 
   bfd_session_control_tx_timer(s, 0);
 
-  birdloop_leave(p->loop);
+  birdloop_leave(p->p.loop);
 
   TRACE(D_EVENTS, "Session to %I reconfigured", s->addr);
 }
@@ -618,9 +626,9 @@ bfd_reconfigure_iface(struct bfd_proto *p, struct bfd_iface *ifa, struct bfd_con
     (new->passive != old->passive);
 
   /* This should be probably changed to not access ifa->cf from the BFD thread */
-  birdloop_enter(p->loop);
+  birdloop_enter(p->p.loop);
   ifa->cf = new;
-  birdloop_leave(p->loop);
+  birdloop_leave(p->p.loop);
 }
 
 
@@ -681,41 +689,68 @@ bfd_add_request(struct bfd_proto *p, struct bfd_request *req)
 }
 
 static void
-bfd_submit_request(struct bfd_request *req)
+bfd_pickup_requests(void *_data UNUSED)
 {
   node *n;
+  WALK_LIST(n, bfd_global.proto_list)
+  {
+    struct bfd_proto *p = SKIP_BACK(struct bfd_proto, bfd_node, n);
+    birdloop_enter(p->p.loop);
+    BFD_LOCK;
 
-  WALK_LIST(n, bfd_proto_list)
-    if (bfd_add_request(SKIP_BACK(struct bfd_proto, bfd_node, n), req))
-      return;
+    node *rn, *rnxt;
+    WALK_LIST_DELSAFE(rn, rnxt, bfd_global.pickup_list)
+      bfd_add_request(p, SKIP_BACK(struct bfd_request, n, rn));
 
-  rem_node(&req->n);
-  add_tail(&bfd_wait_list, &req->n);
-  req->session = NULL;
-  bfd_request_notify(req, BFD_STATE_ADMIN_DOWN, 0);
+    BFD_UNLOCK;
+    birdloop_leave(p->p.loop);
+  }
+
+  BFD_LOCK;
+  node *rn, *rnxt;
+  WALK_LIST_DELSAFE(rn, rnxt, bfd_global.pickup_list)
+  {
+    rem_node(rn);
+    add_tail(&bfd_global.wait_list, rn);
+    bfd_request_notify(SKIP_BACK(struct bfd_request, n, rn), BFD_STATE_ADMIN_DOWN, 0);
+  }
+  BFD_UNLOCK;
 }
 
+static event bfd_pickup_event = { .hook = bfd_pickup_requests };
+
 static void
 bfd_take_requests(struct bfd_proto *p)
 {
   node *n, *nn;
-
-  WALK_LIST_DELSAFE(n, nn, bfd_wait_list)
+  BFD_LOCK;
+  WALK_LIST_DELSAFE(n, nn, bfd_global.wait_list)
     bfd_add_request(p, SKIP_BACK(struct bfd_request, n, n));
+  BFD_UNLOCK;
 }
 
 static void
 bfd_drop_requests(struct bfd_proto *p)
 {
   node *n;
-
-  HASH_WALK(p->session_hash_id, next_id, s)
+  BFD_LOCK;
+  HASH_WALK_DELSAFE(p->session_hash_id, next_id, s)
   {
-    /* We assume that p is not in bfd_proto_list */
     WALK_LIST_FIRST(n, s->request_list)
-      bfd_submit_request(SKIP_BACK(struct bfd_request, n, n));
+    {
+      struct bfd_request *req = SKIP_BACK(struct bfd_request, n, n);
+      rem_node(&req->n);
+      add_tail(&bfd_global.pickup_list, &req->n);
+      req->session = NULL;
+      bfd_request_notify(req, BFD_STATE_ADMIN_DOWN, 0);
+    }
+
+    ev_send(&global_event_list, &bfd_pickup_event);
+
+    bfd_remove_session_locked(p, s);
   }
   HASH_WALK_END;
+  BFD_UNLOCK;
 }
 
 static struct resclass bfd_request_class;
@@ -728,9 +763,6 @@ bfd_request_session(pool *p, ip_addr addr, ip_addr local,
 {
   struct bfd_request *req = ralloc(p, &bfd_request_class);
 
-  /* Hack: self-link req->n, we will call rem_node() on it */
-  req->n.prev = req->n.next = &req->n;
-
   req->addr = addr;
   req->local = local;
   req->iface = iface;
@@ -739,11 +771,16 @@ bfd_request_session(pool *p, ip_addr addr, ip_addr local,
   if (opts)
     req->opts = *opts;
 
-  bfd_submit_request(req);
-
   req->hook = hook;
   req->data = data;
 
+  req->session = NULL;
+
+  BFD_LOCK;
+  add_tail(&bfd_global.pickup_list, &req->n);
+  ev_send(&global_event_list, &bfd_pickup_event);
+  BFD_UNLOCK;
+
   return req;
 }
 
@@ -1001,8 +1038,10 @@ bfd_notify_init(struct bfd_proto *p)
 void
 bfd_init_all(void)
 {
-  init_list(&bfd_proto_list);
-  init_list(&bfd_wait_list);
+  bfd_global.lock = DOMAIN_NEW(rtable, "BFD Global");
+  init_list(&bfd_global.wait_list);
+  init_list(&bfd_global.pickup_list);
+  init_list(&bfd_global.proto_list);
 }
 
 static struct proto *
@@ -1021,10 +1060,10 @@ bfd_start(struct proto *P)
   struct bfd_proto *p = (struct bfd_proto *) P;
   struct bfd_config *cf = (struct bfd_config *) (P->cf);
 
-  p->loop = birdloop_new();
-  p->tpool = rp_new(NULL, "BFD thread root");
   pthread_spin_init(&p->lock, PTHREAD_PROCESS_PRIVATE);
 
+  p->tpool = rp_new(P->pool, "BFD loop pool");
+
   p->session_slab = sl_new(P->pool, sizeof(struct bfd_session));
   HASH_INIT(p->session_hash_id, P->pool, 8);
   HASH_INIT(p->session_hash_ip, P->pool, 8);
@@ -1034,9 +1073,7 @@ bfd_start(struct proto *P)
   init_list(&p->notify_list);
   bfd_notify_init(p);
 
-  add_tail(&bfd_proto_list, &p->bfd_node);
-
-  birdloop_enter(p->loop);
+  add_tail(&bfd_global.proto_list, &p->bfd_node);
 
   if (cf->accept_ipv4 && cf->accept_direct)
     p->rx4_1 = bfd_open_rx_sk(p, 0, SK_IPV4);
@@ -1050,42 +1087,33 @@ bfd_start(struct proto *P)
   if (cf->accept_ipv6 && cf->accept_multihop)
     p->rx6_m = bfd_open_rx_sk(p, 1, SK_IPV6);
 
-  birdloop_leave(p->loop);
-
   bfd_take_requests(p);
 
   struct bfd_neighbor *n;
   WALK_LIST(n, cf->neigh_list)
     bfd_start_neighbor(p, n);
 
-  birdloop_start(p->loop);
-
   return PS_UP;
 }
 
-
 static int
 bfd_shutdown(struct proto *P)
 {
   struct bfd_proto *p = (struct bfd_proto *) P;
-  struct bfd_config *cf = (struct bfd_config *) (P->cf);
+  struct bfd_config *cf = (struct bfd_config *) (p->p.cf);
 
   rem_node(&p->bfd_node);
 
-  birdloop_stop(p->loop);
-
-  struct bfd_neighbor *n;
-  WALK_LIST(n, cf->neigh_list)
-    bfd_stop_neighbor(p, n);
+  struct bfd_neighbor *bn;
+  WALK_LIST(bn, cf->neigh_list)
+    bfd_stop_neighbor(p, bn);
 
   bfd_drop_requests(p);
 
-  /* FIXME: This is hack */
-  birdloop_enter(p->loop);
-  rfree(p->tpool);
-  birdloop_leave(p->loop);
-
-  birdloop_free(p->loop);
+  if (p->rx4_1) sk_stop(p->rx4_1);
+  if (p->rx4_m) sk_stop(p->rx4_m);
+  if (p->rx6_1) sk_stop(p->rx6_1);
+  if (p->rx6_m) sk_stop(p->rx6_m);
 
   return PS_DOWN;
 }
@@ -1105,7 +1133,7 @@ bfd_reconfigure(struct proto *P, struct proto_config *c)
       (new->accept_multihop != old->accept_multihop))
     return 0;
 
-  birdloop_mask_wakeups(p->loop);
+  birdloop_mask_wakeups(p->p.loop);
 
   WALK_LIST(ifa, p->iface_list)
     bfd_reconfigure_iface(p, ifa, new);
@@ -1119,7 +1147,7 @@ bfd_reconfigure(struct proto *P, struct proto_config *c)
 
   bfd_reconfigure_neighbors(p, new);
 
-  birdloop_unmask_wakeups(p->loop);
+  birdloop_unmask_wakeups(p->p.loop);
 
   return 1;
 }