vlib: add VLIB_NUM_WORKERS_CHANGE_FN() handler

Allows features to update their data structures after change in number
of worker threads.

Type: improvement
Change-Id: Icd4d197e28608f5bbb1edd13eb624cd98e33cafe
Signed-off-by: Damjan Marion <damarion@cisco.com>

src/vlib/buffer.c

@@ -636,25 +636,19 @@ VLIB_CLI_COMMAND (show_buffers_command, static) = {
 /* *INDENT-ON* */
 
 clib_error_t *
-vlib_buffer_worker_init (vlib_main_t * vm)
+vlib_buffer_num_workers_change (vlib_main_t *vm)
 {
   vlib_buffer_main_t *bm = vm->buffer_main;
   vlib_buffer_pool_t *bp;
 
-  /* *INDENT-OFF* */
   vec_foreach (bp, bm->buffer_pools)
-    {
-      clib_spinlock_lock (&bp->lock);
-      vec_validate_aligned (bp->threads, vlib_get_n_threads () - 1,
-			    CLIB_CACHE_LINE_BYTES);
-      clib_spinlock_unlock (&bp->lock);
-    }
-  /* *INDENT-ON* */
+    vec_validate_aligned (bp->threads, vlib_get_n_threads () - 1,
+			  CLIB_CACHE_LINE_BYTES);
 
   return 0;
 }
 
-VLIB_WORKER_INIT_FUNCTION (vlib_buffer_worker_init);
+VLIB_NUM_WORKERS_CHANGE_FN (vlib_buffer_num_workers_change);
 
 static clib_error_t *
 vlib_buffer_main_init_numa_alloc (struct vlib_main_t *vm, u32 numa_node,

src/vlib/init.h

@@ -171,6 +171,8 @@ static __clib_unused void * __clib_unused_##tag##_##x = x
 
 #define VLIB_INIT_FUNCTION(x) VLIB_DECLARE_INIT_FUNCTION(x,init)
 #define VLIB_WORKER_INIT_FUNCTION(x) VLIB_DECLARE_INIT_FUNCTION(x,worker_init)
+#define VLIB_NUM_WORKERS_CHANGE_FN(x)                                         \
+  VLIB_DECLARE_INIT_FUNCTION (x, num_workers_change)
 
 #define VLIB_MAIN_LOOP_ENTER_FUNCTION(x) \
   VLIB_DECLARE_INIT_FUNCTION(x,main_loop_enter)

src/vlib/main.h

@@ -306,6 +306,7 @@ typedef struct vlib_global_main_t
   _vlib_init_function_list_elt_t *main_loop_enter_function_registrations;
   _vlib_init_function_list_elt_t *main_loop_exit_function_registrations;
   _vlib_init_function_list_elt_t *worker_init_function_registrations;
+  _vlib_init_function_list_elt_t *num_workers_change_function_registrations;
   _vlib_init_function_list_elt_t *api_init_function_registrations;
   vlib_config_function_runtime_t *config_function_registrations;
 

src/vlib/threads.c

@@ -820,6 +820,14 @@ start_workers (vlib_main_t * vm)
 	}
     }
   vlib_worker_thread_barrier_sync (vm);
+  {
+    clib_error_t *err;
+    err = vlib_call_init_exit_functions (
+      vm, &vgm->num_workers_change_function_registrations, 1 /* call_once */,
+      1 /* is_global */);
+    if (err)
+      clib_error_report (err);
+  }
   vlib_worker_thread_barrier_release (vm);
   return 0;
 }