BUG#53657: Slave crashed with error 22 when trying to lock mutex

           at mf_iocache.c, line 1722

The slave crashed while two threads: IO thread and user thread
raced for the same mutex (the append_buffer_lock protecting the
relay log's IO_CACHE). The IO thread was trying to flush the
cache, and for that was grabbing the append_buffer_lock. 

However, the other thread was closing and reopening the relay log
when the IO thread tried to lock. Closing and reopening the log
includes destroying and reinitialising the IO_CACHE
mutex. Therefore, the IO thread tried to lock a destroyed mutex.

We fix this by backporting patch for BUG#50364 which fixed this
bug in mysql server 5.5+. The patch deploys missing
synchronization when flush_master_info is called and the relay
log is flushed by the IO thread. In detail the patch backports
revision (from mysql-trunk):
- luis.soares@sun.com-20100203165617-b1yydr0ee24ycpjm

This patch already includes the post-push fix also in BUG#50364:
- luis.soares@sun.com-20100222002629-0cijwqk6baxhj7gr

1 files changed, 1 insertions, 1 deletions

diff --git a/sql/sql_repl.cc b/sql/sql_repl.cc
index c220f609c09..75a738a0073 100644
--- a/sql/sql_repl.cc
+++ b/sql/sql_repl.cc
@@ -1282,7 +1282,7 @@ bool change_master(THD* thd, Master_info* mi)
     Relay log's IO_CACHE may not be inited, if rli->inited==0 (server was never
     a slave before).
   */
-  if (flush_master_info(mi, 0))
+  if (flush_master_info(mi, FALSE, FALSE))
   {
     my_error(ER_RELAY_LOG_INIT, MYF(0), "Failed to flush master info file");
     unlock_slave_threads(mi);