dpif: Allow adding ukeys for same flow by different pmds.

In multiqueue mode several pmd threads may process one port, but
different queues. Flow may not depend on queue. It's true at least for
vhost-user ports.

When multiple pmd threads attempt to process upcalls for a particular
flow key, only the first will succeed. Any subsequent threads will
receive error = ENOSPC when attempting to insert a new udpif_key into
the umaps. This causes the latter threads to never insert a flow into
the datapath to handle the traffic, and as a result they will
consistently execute those flows through the slow path.

Fix that by mixing pmd_id with the bits from the ufid for ukey->hash
calculation. So, for a given flow key/UFID, each pmd thread will create
an independent udpif_key.

This also opens the possibility to reassign queues among pmd threads
without restarting them and deleting the megaflow cache.

Signed-off-by: Ilya Maximets <[email protected]>
Signed-off-by: Joe Stringer <[email protected]>

ofproto/ofproto-dpif-upcall.c

@@ -341,7 +341,8 @@ static bool ukey_install_start(struct udpif *, struct udpif_key *ukey);
 static bool ukey_install_finish(struct udpif_key *ukey, int error);
 static bool ukey_install(struct udpif *udpif, struct udpif_key *ukey);
 static struct udpif_key *ukey_lookup(struct udpif *udpif,
-                                     const ovs_u128 *ufid);
+                                     const ovs_u128 *ufid,
+                                     const unsigned pmd_id);
 static int ukey_acquire(struct udpif *, const struct dpif_flow *,
                         struct udpif_key **result, int *error);
 static void ukey_delete__(struct udpif_key *);
@@ -1223,7 +1224,8 @@ process_upcall(struct udpif *udpif, struct upcall *upcall,
             }
             if (actions_len == 0) {
                 /* Lookup actions in userspace cache. */
-                struct udpif_key *ukey = ukey_lookup(udpif, upcall->ufid);
+                struct udpif_key *ukey = ukey_lookup(udpif, upcall->ufid,
+                                                     upcall->pmd_id);
                 if (ukey) {
                     ukey_get_actions(ukey, &actions, &actions_len);
                     dpif_sflow_read_actions(flow, actions, actions_len,
@@ -1398,19 +1400,20 @@ handle_upcalls(struct udpif *udpif, struct upcall *upcalls,
 }
 
 static uint32_t
-get_ufid_hash(const ovs_u128 *ufid)
+get_ukey_hash(const ovs_u128 *ufid, const unsigned pmd_id)
 {
-    return ufid->u32[0];
+    return hash_2words(ufid->u32[0], pmd_id);
 }
 
 static struct udpif_key *
-ukey_lookup(struct udpif *udpif, const ovs_u128 *ufid)
+ukey_lookup(struct udpif *udpif, const ovs_u128 *ufid, const unsigned pmd_id)
 {
     struct udpif_key *ukey;
-    int idx = get_ufid_hash(ufid) % N_UMAPS;
+    int idx = get_ukey_hash(ufid, pmd_id) % N_UMAPS;
     struct cmap *cmap = &udpif->ukeys[idx].cmap;
 
-    CMAP_FOR_EACH_WITH_HASH (ukey, cmap_node, get_ufid_hash(ufid), cmap) {
+    CMAP_FOR_EACH_WITH_HASH (ukey, cmap_node,
+                             get_ukey_hash(ufid, pmd_id), cmap) {
         if (ovs_u128_equals(&ukey->ufid, ufid)) {
             return ukey;
         }
@@ -1456,7 +1459,7 @@ ukey_create__(const struct nlattr *key, size_t key_len,
     ukey->ufid_present = ufid_present;
     ukey->ufid = *ufid;
     ukey->pmd_id = pmd_id;
-    ukey->hash = get_ufid_hash(&ukey->ufid);
+    ukey->hash = get_ukey_hash(&ukey->ufid, pmd_id);
 
     ovsrcu_init(&ukey->actions, NULL);
     ukey_set_actions(ukey, actions);
@@ -1589,7 +1592,7 @@ ukey_install_start(struct udpif *udpif, struct udpif_key *new_ukey)
     idx = new_ukey->hash % N_UMAPS;
     umap = &udpif->ukeys[idx];
     ovs_mutex_lock(&umap->mutex);
-    old_ukey = ukey_lookup(udpif, &new_ukey->ufid);
+    old_ukey = ukey_lookup(udpif, &new_ukey->ufid, new_ukey->pmd_id);
     if (old_ukey) {
         /* Uncommon case: A ukey is already installed with the same UFID. */
         if (old_ukey->key_len == new_ukey->key_len
@@ -1671,7 +1674,7 @@ ukey_acquire(struct udpif *udpif, const struct dpif_flow *flow,
     struct udpif_key *ukey;
     int retval;
 
-    ukey = ukey_lookup(udpif, &flow->ufid);
+    ukey = ukey_lookup(udpif, &flow->ufid, flow->pmd_id);
     if (ukey) {
         retval = ovs_mutex_trylock(&ukey->mutex);
     } else {