Fix for BUG#2921 "Replication problem on mutex lock in mySQL-4.0.18":

re-using unused LOCK_active_mi to serialize all administrative
commands related to replication:
START SLAVE, STOP SLAVE, RESET SLAVE, CHANGE MASTER, init_slave()
(replication autostart at server startup), end_slave() (replication
autostop at server shutdown), LOAD DATA FROM MASTER.
This protects us against a handful of deadlocks (like BUG#2921
when two START SLAVE, but when two STOP SLAVE too).
Removing unused variables.


sql/item_func.cc:
  We don't need LOCK_active_mi just to MASTER_POS_WAIT().
sql/repl_failsafe.cc:
  no need for macro
sql/set_var.cc:
  no need for macro
sql/slave.cc:
  Re-using unused LOCK_active_mi to serialize all administrative
  commands related to replication:
  START SLAVE, STOP SLAVE, RESET SLAVE, CHANGE MASTER, init_slave()
  (replication autostart at server startup), end_slave() (replication
  autostop at server shutdown), LOAD DATA FROM MASTER.
  This protects us against a handful of deadlocks.
  Removing unused variables.
sql/slave.h:
  Re-using LOCK_active_mi to serialize administrative replication commands.
  Macros unneeded. Removing unneeded variables.
sql/sql_parse.cc:
  found unused variable.
  Replacing macros.
sql/sql_show.cc:
  replacing macros

1 files changed, 4 insertions, 4 deletions

diff --git a/sql/repl_failsafe.cc b/sql/repl_failsafe.cc
index 56789a01bf4..e687b227946 100644
--- a/sql/repl_failsafe.cc
+++ b/sql/repl_failsafe.cc
@@ -750,7 +750,7 @@ int load_master_data(THD* thd)
     We do not want anyone messing with the slave at all for the entire
     duration of the data load.
   */
-  LOCK_ACTIVE_MI;
+  pthread_mutex_lock(&LOCK_active_mi);
   lock_slave_threads(active_mi);
   init_thread_mask(&restart_thread_mask,active_mi,0 /*not inverse*/);
   if (restart_thread_mask &&
@@ -759,7 +759,7 @@ int load_master_data(THD* thd)
   {
     send_error(&thd->net,error);
     unlock_slave_threads(active_mi);
-    UNLOCK_ACTIVE_MI;
+    pthread_mutex_unlock(&LOCK_active_mi);
     return 1;
   }
   
@@ -913,7 +913,7 @@ int load_master_data(THD* thd)
   {
     send_error(&thd->net, 0, "Failed purging old relay logs");
     unlock_slave_threads(active_mi);
-    UNLOCK_ACTIVE_MI;
+    pthread_mutex_unlock(&LOCK_active_mi);
     return 1;
   }
   pthread_mutex_lock(&active_mi->rli.data_lock);
@@ -934,7 +934,7 @@ int load_master_data(THD* thd)
 
 err:
   unlock_slave_threads(active_mi);
-  UNLOCK_ACTIVE_MI;
+  pthread_mutex_unlock(&LOCK_active_mi);
   thd->proc_info = 0;
 
   mc_mysql_close(&mysql); // safe to call since we always do mc_mysql_init()