perfschema: LOCK_all_status_vars not LOCK_status

to iterate over all status variables one should use
LOCK_all_status_vars not LOCK_status

this fixes sporadic mutex lock inversion in plugins.password_reuse_check:
* acl_cache->lock is taken over complex operations that might increment
  status counters (under LOCK_status).
* acl_cache->lock is needed to get the values of Acl% status variables
  when iterating over status variables

storage/perfschema/pfs_variable.cc

@@ -762,7 +762,7 @@ bool PFS_status_variable_cache::filter_show_var(const SHOW_VAR *show_var, bool s
 /**
   Build an array of SHOW_VARs from the global status array. Expand nested
   subarrays, filter unwanted variables.
-  NOTE: Must be done inside of LOCK_status to guard against plugin load/unload.
+  NOTE: Must be done under LOCK_all_status_vars
 */
 bool PFS_status_variable_cache::init_show_var_array(enum_var_type scope, bool strict)
 {
@@ -881,14 +881,12 @@ char * PFS_status_variable_cache::make_show_var_name(const char* prefix, const c
 */
 bool PFS_status_variable_cache::do_initialize_session(void)
 {
-  /* Acquire LOCK_status to guard against plugin load/unload. */
-  //if (m_current_thd->fill_status_recursion_level++ == 0)
-    mysql_mutex_lock(&LOCK_status);
+  /* Acquire LOCK_all_status_vars to guard against plugin load/unload. */
+  mysql_rwlock_rdlock(&LOCK_all_status_vars);
 
   bool ret= init_show_var_array(OPT_SESSION, true);
 
-  //if (m_current_thd->fill_status_recursion_level-- == 1)
-    mysql_mutex_unlock(&LOCK_status);
+  mysql_rwlock_unlock(&LOCK_all_status_vars);
 
   return ret;
 }
@@ -917,13 +915,12 @@ int PFS_status_variable_cache::do_materialize_global(void)
   m_materialized= false;
   DEBUG_SYNC(m_current_thd, "before_materialize_global_status_array");
 
-  /* Acquire LOCK_status to guard against plugin load/unload. */
-  //if (m_current_thd->fill_status_recursion_level++ == 0)
-    mysql_mutex_lock(&LOCK_status);
+  /* Acquire LOCK_all_status_vars to guard against plugin load/unload. */
+  mysql_rwlock_rdlock(&LOCK_all_status_vars);
 
   /*
-     Build array of SHOW_VARs from global status array. Do this within
-     LOCK_status to ensure that the array remains unchanged during
+     Build array of SHOW_VARs from global status array. Do this under
+     LOCK_all_status_vars to ensure that the array remains unchanged during
      materialization.
    */
   if (!m_external_init)
@@ -946,8 +943,7 @@ int PFS_status_variable_cache::do_materialize_global(void)
   */
   manifest(m_current_thd, m_show_var_array.front(), &status_totals, "", false, true);
 
-  //if (m_current_thd->fill_status_recursion_level-- == 1)
-    mysql_mutex_unlock(&LOCK_status);
+  mysql_rwlock_unlock(&LOCK_all_status_vars);
 
   m_materialized= true;
   DEBUG_SYNC(m_current_thd, "after_materialize_global_status_array");
@@ -967,13 +963,11 @@ int PFS_status_variable_cache::do_materialize_all(THD* unsafe_thd)
   m_materialized= false;
   m_cache.clear();
 
-  /* Avoid recursive acquisition of LOCK_status. */
-  //if (m_current_thd->fill_status_recursion_level++ == 0)
-    mysql_mutex_lock(&LOCK_status);
+  mysql_rwlock_rdlock(&LOCK_all_status_vars);
 
   /*
-     Build array of SHOW_VARs from global status array. Do this within
-     LOCK_status to ensure that the array remains unchanged while this
+     Build array of SHOW_VARs from global status array. Do this under
+     LOCK_all_status_vars to ensure that the array remains unchanged while this
      thread is materialized.
    */
   if (!m_external_init)
@@ -996,8 +990,7 @@ int PFS_status_variable_cache::do_materialize_all(THD* unsafe_thd)
     ret= 0;
   }
 
-  //if (m_current_thd->fill_status_recursion_level-- == 1)
-    mysql_mutex_unlock(&LOCK_status);
+  mysql_rwlock_unlock(&LOCK_all_status_vars);
   return ret;
 }
 
@@ -1013,13 +1006,11 @@ int PFS_status_variable_cache::do_materialize_session(THD* unsafe_thd)
   m_materialized= false;
   m_cache.clear();
 
-  /* Avoid recursive acquisition of LOCK_status. */
-  //if (m_current_thd->fill_status_recursion_level++ == 0)
-    mysql_mutex_lock(&LOCK_status);
+  mysql_rwlock_rdlock(&LOCK_all_status_vars);
 
   /*
-     Build array of SHOW_VARs from global status array. Do this within
-     LOCK_status to ensure that the array remains unchanged while this
+     Build array of SHOW_VARs from global status array. Do this under
+     LOCK_all_status_vars to ensure that the array remains unchanged while this
      thread is materialized.
    */
   if (!m_external_init)
@@ -1042,8 +1033,7 @@ int PFS_status_variable_cache::do_materialize_session(THD* unsafe_thd)
     ret= 0;
   }
 
-  //if (m_current_thd->fill_status_recursion_level-- == 1)
-    mysql_mutex_unlock(&LOCK_status);
+  mysql_rwlock_unlock(&LOCK_all_status_vars);
   return ret;
 }
 
@@ -1060,9 +1050,8 @@ int PFS_status_variable_cache::do_materialize_session(PFS_thread *pfs_thread)
   m_materialized= false;
   m_cache.clear();
 
-  /* Acquire LOCK_status to guard against plugin load/unload. */
-  //if (m_current_thd->fill_status_recursion_level++ == 0)
-    mysql_mutex_lock(&LOCK_status);
+  /* Acquire LOCK_all_status_vars to guard against plugin load/unload. */
+  mysql_rwlock_rdlock(&LOCK_all_status_vars);
 
   /* The SHOW_VAR array must be initialized externally. */
   assert(m_initialized);
@@ -1084,8 +1073,7 @@ int PFS_status_variable_cache::do_materialize_session(PFS_thread *pfs_thread)
     ret= 0;
   }
 
-  //if (m_current_thd->fill_status_recursion_level-- == 1)
-    mysql_mutex_unlock(&LOCK_status);
+  mysql_rwlock_unlock(&LOCK_all_status_vars);
   return ret;
 }
 
@@ -1104,9 +1092,8 @@ int PFS_status_variable_cache::do_materialize_client(PFS_client *pfs_client)
   m_materialized= false;
   m_cache.clear();
 
-  /* Acquire LOCK_status to guard against plugin load/unload. */
-  //if (m_current_thd->fill_status_recursion_level++ == 0)
-    mysql_mutex_lock(&LOCK_status);
+  /* Acquire LOCK_all_status_vars to guard against plugin load/unload. */
+  mysql_rwlock_rdlock(&LOCK_all_status_vars);
 
   /* The SHOW_VAR array must be initialized externally. */
   assert(m_initialized);
@@ -1123,8 +1110,7 @@ int PFS_status_variable_cache::do_materialize_client(PFS_client *pfs_client)
   */
   manifest(m_current_thd, m_show_var_array.front(), &status_totals, "", false, true);
 
-  //if (m_current_thd->fill_status_recursion_level-- == 1)
-    mysql_mutex_unlock(&LOCK_status);
+  mysql_rwlock_unlock(&LOCK_all_status_vars);
 
   m_materialized= true;
   return 0;
@@ -1217,7 +1203,7 @@ Status_variable::Status_variable(const SHOW_VAR *show_var, STATUS_VAR *status_va
 /**
   Resolve status value, convert to string.
   show_var->value is an offset into status_vars.
-  NOTE: Assumes LOCK_status is held.
+  NOTE: Assumes LOCK_all_status_vars is held.
 */
 void Status_variable::init(const SHOW_VAR *show_var, STATUS_VAR *status_vars, enum_var_type query_scope)
 {
@@ -1283,7 +1269,7 @@ void sum_account_status(PFS_client *pfs_account, STATUS_VAR *status_totals)
 
 /**
   Reset aggregated status counter stats for account, user and host.
-  NOTE: Assumes LOCK_status is held.
+  NOTE: Assumes LOCK_all_status_vars is held.
 */
 void reset_pfs_status_stats()
 {

storage/perfschema/pfs_visitor.cc

@@ -1356,8 +1356,7 @@ PFS_connection_status_visitor::~PFS_connection_status_visitor() = default;
 /** Aggregate from global status. */
 void PFS_connection_status_visitor::visit_global()
 {
-   /* NOTE: Requires lock on LOCK_status. */
-   mysql_mutex_assert_owner(&LOCK_status);
+   /* NOTE: Requires lock on LOCK_all_status_vars. */
    add_to_status(m_status_vars, &global_status_var);
 }