vlib: add plugin override support

Allow a plugin to override (suppress loading of) other plugins. This
mechanism allows a developer to prevent specific plugins from being
loaded.

To do so, provide an "overrides" list in the plugin definition:

VLIB_PLUGIN_REGISTER () =
{
  <snip>
  .overrides = "avf_plugin.so,ioam_plugin.so,dpdk_plugin.so",
};

or some such. Simply list the plugins in question as shown above. The
.overrides structure member is limited to 256 octets. The named .elf
section mechanism used to discover the vlib_plugin_registration_t's
precludes the use of a variable-length array of strings.

Use the vlib log to eliminate plugin and built-in vat plugin loader
console spew.

Added vlib_log_register_class_rate_limit(...) to allow procedural
configuration of the log rate-limit. We *never* want to rate-limit
plugin loader messages.

Type: feature

Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: I0a9327b8cf5508482f057342783252112cb44170

src/vlib/log.c

@@ -172,8 +172,8 @@ syslog:
 
 }
 
-vlib_log_class_t
-vlib_log_register_class (char *class, char *subclass)
+static vlib_log_class_t
+vlib_log_register_class_internal (char *class, char *subclass, u32 limit)
 {
   vlib_log_main_t *lm = &log_main;
   vlib_log_class_data_t *c = NULL;
@@ -199,12 +199,26 @@ vlib_log_register_class (char *class, char *subclass)
   vec_add2 (c->subclasses, s, 1);
   s->index = s - c->subclasses;
   s->name = subclass ? format (0, "%s", subclass) : 0;
-  s->rate_limit = lm->default_rate_limit;
+  s->rate_limit = (limit == 0) ? lm->default_rate_limit : limit;
   s->level = lm->default_log_level;
   s->syslog_level = lm->default_syslog_log_level;
   return (c->index << 16) | (s->index);
 }
 
+vlib_log_class_t
+vlib_log_register_class (char *class, char *subclass)
+{
+  return vlib_log_register_class_internal (class, subclass,
+					   0 /* default rate limit */ );
+}
+
+vlib_log_class_t
+vlib_log_register_class_rate_limit (char *class, char *subclass, u32 limit)
+{
+  return vlib_log_register_class_internal (class, subclass, limit);
+}
+
+
 u8 *
 format_vlib_log_level (u8 * s, va_list * args)
 {

src/vlib/log.h

@@ -90,6 +90,9 @@ typedef struct
 extern vlib_log_main_t log_main;
 
 vlib_log_class_t vlib_log_register_class (char *vlass, char *subclass);
+vlib_log_class_t
+vlib_log_register_class_rate_limit (char *class, char *subclass,
+				    u32 rate_limit);
 u32 vlib_log_get_indent ();
 void vlib_log (vlib_log_level_t level, vlib_log_class_t class, char *fmt,
 	       ...);

src/vlib/main.c

@@ -2021,8 +2021,6 @@ vlib_main (vlib_main_t * volatile vm, unformat_input_t * input)
 
   vm->queue_signal_callback = dummy_queue_signal_callback;
 
-  clib_time_init (&vm->clib_time);
-
   /* Turn on event log. */
   if (!vm->elog_main.event_ring_size)
     vm->elog_main.event_ring_size = 128 << 10;

src/vlib/unix/main.c

@@ -685,6 +685,8 @@ vlib_unix_main (int argc, char *argv[])
     (((uword) vm->heap_base) & ~(VLIB_FRAME_ALIGN - 1));
   ASSERT (vm->heap_base);
 
+  clib_time_init (&vm->clib_time);
+
   unformat_init_command_line (&input, (char **) vm->argv);
   if ((e = vlib_plugin_config (vm, &input)))
     {

src/vlib/unix/plugin.h

@@ -61,6 +61,7 @@ typedef CLIB_PACKED(struct {
   u8 default_disabled;
   const char version[32];
   const char version_required[32];
+  const char overrides[256];
   const char *early_init;
   const char *description;
 }) vlib_plugin_registration_t;
@@ -91,6 +92,7 @@ typedef struct
   /* loaded plugin info */
   plugin_info_t *plugin_info;
   uword *plugin_by_name_hash;
+  uword *plugin_overrides_by_name_hash;
 
   /* paths and name filters */
   u8 *plugin_path;
@@ -103,6 +105,9 @@ typedef struct
   plugin_config_t *configs;
   uword *config_index_by_name;
 
+  /* Plugin log, avoid filling syslog w/ junk */
+  vlib_log_class_t logger;
+
   /* usual */
   vlib_main_t *vlib_main;
 } plugin_main_t;

src/vpp/api/plugin.c

@@ -23,6 +23,15 @@
 
 plugin_main_t vat_plugin_main;
 
+static vlib_log_class_t vat_builtin_logger;
+
+#define PLUGIN_LOG_DBG(...) \
+  do {vlib_log_debug (vat_builtin_logger, __VA_ARGS__);} while(0)
+#define PLUGIN_LOG_ERR(...) \
+  do {vlib_log_err (vat_builtin_logger, __VA_ARGS__);} while(0)
+#define PLUGIN_LOG_NOTICE(...) \
+  do {vlib_log_notice (vat_builtin_logger, __VA_ARGS__);} while(0)
+
 static int
 load_one_vat_plugin (plugin_main_t * pm, plugin_info_t * pi)
 {
@@ -39,7 +48,7 @@ load_one_vat_plugin (plugin_main_t * pm, plugin_info_t * pi)
    */
   if (handle == 0)
     {
-      clib_warning ("%s", dlerror ());
+      PLUGIN_LOG_ERR ("%s", dlerror ());
       return 0;
     }
 
@@ -48,7 +57,7 @@ load_one_vat_plugin (plugin_main_t * pm, plugin_info_t * pi)
   register_handle = dlsym (pi->handle, "vat_plugin_register");
   if (register_handle == 0)
     {
-      clib_warning ("%s: symbol vat_plugin_register not found", pi->name);
+      PLUGIN_LOG_ERR ("%s: symbol vat_plugin_register not found", pi->name);
       dlclose (handle);
       return 0;
     }
@@ -59,12 +68,15 @@ load_one_vat_plugin (plugin_main_t * pm, plugin_info_t * pi)
 
   if (error)
     {
-      clib_error_report (error);
+      u8 *err = format (0, "%U%c", format_clib_error, error, 0);
+      PLUGIN_LOG_ERR ((char *) err);
+      clib_error_free (error);
       dlclose (handle);
+      pi->handle = 0;
       return 1;
     }
 
-  clib_warning ("Loaded plugin: %s", pi->name);
+  PLUGIN_LOG_NOTICE ("Loaded plugin: %s", pi->name);
 
   return 0;
 }
@@ -190,6 +202,10 @@ vat_plugin_init (vat_main_t * vam)
   u8 *plugin_path;
   u8 *plugin_name_filter;
 
+  vat_builtin_logger =
+    vlib_log_register_class_rate_limit ("vat-plug", "load",
+					0x7FFFFFFF /* aka no rate limit */ );
+
   plugin_path = vlib_get_vat_plugin_path ();
   plugin_name_filter = vlib_get_vat_plugin_name_filter ();