session: fix workers race to allocate lookup table

[vpp.git] / src / vnet / session / session_lookup.c

diff --git a/src/vnet/session/session_lookup.c b/src/vnet/session/session_lookup.c
index 335905d..9d028db 100644 (file)
--- a/src/vnet/session/session_lookup.c
+++ b/src/vnet/session/session_lookup.c
@@ -29,13 +29,14 @@
 #include <vnet/session/session.h>
 #include <vnet/session/application.h>
 
+static session_lookup_main_t sl_main;
+
 /**
  * Network namespace index (i.e., fib index) to session lookup table. We
  * should have one per network protocol type but for now we only support IP4/6
  */
 static u32 *fib_index_to_table_index[2];
 
-/* *INDENT-OFF* */
 /* 16 octets */
 typedef CLIB_PACKED (struct {
   union
@@ -72,7 +73,6 @@ typedef CLIB_PACKED (struct {
       u64 as_u64[6];
     };
 }) v6_connection_key_t;
-/* *INDENT-ON* */
 
 typedef clib_bihash_kv_16_8_t session_kv4_t;
 typedef clib_bihash_kv_48_8_t session_kv6_t;
@@ -155,29 +155,70 @@ make_v6_ss_kv_from_tc (session_kv6_t * kv, transport_connection_t * tc)
                 tc->rmt_port, tc->proto);
 }
 
+static inline u8
+session_table_alloc_needs_sync (void)
+{
+  return !vlib_thread_is_main_w_barrier () && (vlib_num_workers () > 1);
+}
+
+static_always_inline u8
+session_table_is_alloced (u8 fib_proto, u32 fib_index)
+{
+  return (vec_len (fib_index_to_table_index[fib_proto]) > fib_index &&
+         fib_index_to_table_index[fib_proto][fib_index] != ~0);
+}
+
 static session_table_t *
 session_table_get_or_alloc (u8 fib_proto, u32 fib_index)
 {
   session_table_t *st;
   u32 table_index;
+
   ASSERT (fib_index != ~0);
-  if (vec_len (fib_index_to_table_index[fib_proto]) > fib_index &&
-      fib_index_to_table_index[fib_proto][fib_index] != ~0)
+
+  if (session_table_is_alloced (fib_proto, fib_index))
     {
       table_index = fib_index_to_table_index[fib_proto][fib_index];
       return session_table_get (table_index);
     }
+
+  u8 needs_sync = session_table_alloc_needs_sync ();
+  session_lookup_main_t *slm = &sl_main;
+
+  /* Stop workers, otherwise consumers might be affected. This is
+   * acceptable because new tables should seldom be allocated */
+  if (needs_sync)
+    {
+      vlib_workers_sync ();
+
+      /* We might have a race, only one worker allowed at once */
+      clib_spinlock_lock (&slm->st_alloc_lock);
+    }
+
+  /* Another worker just allocated this table */
+  if (session_table_is_alloced (fib_proto, fib_index))
+    {
+      table_index = fib_index_to_table_index[fib_proto][fib_index];
+      st = session_table_get (table_index);
+    }
   else
     {
       st = session_table_alloc ();
-      table_index = session_table_index (st);
+      st->active_fib_proto = fib_proto;
+      session_table_init (st, fib_proto);
       vec_validate_init_empty (fib_index_to_table_index[fib_proto], fib_index,
                               ~0);
+      table_index = session_table_index (st);
       fib_index_to_table_index[fib_proto][fib_index] = table_index;
-      st->active_fib_proto = fib_proto;
-      session_table_init (st, fib_proto);
-      return st;
     }
+
+  if (needs_sync)
+    {
+      clib_spinlock_unlock (&slm->st_alloc_lock);
+      vlib_workers_continue ();
+    }
+
+  return st;
 }
 
 static session_table_t *
@@ -1569,7 +1610,6 @@ done:
   return error;
 }
 
-/* *INDENT-OFF* */
 VLIB_CLI_COMMAND (session_rule_command, static) =
 {
   .path = "session rule",
@@ -1577,7 +1617,6 @@ VLIB_CLI_COMMAND (session_rule_command, static) =
       "<lcl-ip/plen> <lcl-port> <rmt-ip/plen> <rmt-port> action <action>",
   .function = session_rule_command_fn,
 };
-/* *INDENT-ON* */
 
 void
 session_lookup_dump_rules_table (u32 fib_index, u8 fib_proto,
@@ -1700,7 +1739,6 @@ show_session_rules_command_fn (vlib_main_t * vm, unformat_input_t * input,
   return 0;
 }
 
-/* *INDENT-OFF* */
 VLIB_CLI_COMMAND (show_session_rules_command, static) =
 {
   .path = "show session rules",
@@ -1708,7 +1746,6 @@ VLIB_CLI_COMMAND (show_session_rules_command, static) =
       "<lcl-port> <rmt-ip/plen> <rmt-port> scope <scope>]",
   .function = show_session_rules_command_fn,
 };
-/* *INDENT-ON* */
 
 u8 *
 format_session_lookup_tables (u8 *s, va_list *args)
@@ -1792,6 +1829,10 @@ VLIB_CLI_COMMAND (show_session_lookup_command, static) = {
 void
 session_lookup_init (void)
 {
+  session_lookup_main_t *slm = &sl_main;
+
+  clib_spinlock_init (&slm->st_alloc_lock);
+
   /*
    * Allocate default table and map it to fib_index 0
    */