Bug #12969156: SEGMENTATION FAULT ON UNINSTALLING

DAEMON_EXAMPLE PLUGIN

The deinit() function of the daemon example plugin was 
calling pthread_cancel, but not waiting for the worker 
thread to actually complete before deallocating the data
buffer and closing the file that it writes to.
Fixed by adding a pthread_join to wait for the thread 
to complete before doing the cleanup work that may 
affect it.
Test case added.
Removed a stray 'x' variable from the example code.

Author: gkodinov

mysql-test/r/bug12969156.result

@@ -0,0 +1,24 @@
+#
+# Bug #12969156 : SEGMENTATION FAULT ON UNINSTALLING
+#  DAEMON_EXAMPLE PLUGIN
+#
+INSTALL PLUGIN daemon_example SONAME 'DAEMONEXAMPLE';
+UNINSTALL PLUGIN daemon_example;
+INSTALL PLUGIN daemon_example SONAME 'DAEMONEXAMPLE';
+UNINSTALL PLUGIN daemon_example;
+INSTALL PLUGIN daemon_example SONAME 'DAEMONEXAMPLE';
+UNINSTALL PLUGIN daemon_example;
+INSTALL PLUGIN daemon_example SONAME 'DAEMONEXAMPLE';
+UNINSTALL PLUGIN daemon_example;
+INSTALL PLUGIN daemon_example SONAME 'DAEMONEXAMPLE';
+UNINSTALL PLUGIN daemon_example;
+INSTALL PLUGIN daemon_example SONAME 'DAEMONEXAMPLE';
+UNINSTALL PLUGIN daemon_example;
+INSTALL PLUGIN daemon_example SONAME 'DAEMONEXAMPLE';
+UNINSTALL PLUGIN daemon_example;
+INSTALL PLUGIN daemon_example SONAME 'DAEMONEXAMPLE';
+UNINSTALL PLUGIN daemon_example;
+INSTALL PLUGIN daemon_example SONAME 'DAEMONEXAMPLE';
+UNINSTALL PLUGIN daemon_example;
+INSTALL PLUGIN daemon_example SONAME 'DAEMONEXAMPLE';
+UNINSTALL PLUGIN daemon_example;

mysql-test/t/bug12969156-master.opt

@@ -0,0 +1 @@
+--plugin-dir=$DAEMONEXAMPLE_DIR

mysql-test/t/bug12969156.test

@@ -0,0 +1,15 @@
+--source include/not_embedded.inc
+
+--echo #
+--echo # Bug #12969156 : SEGMENTATION FAULT ON UNINSTALLING
+--echo #  DAEMON_EXAMPLE PLUGIN
+--echo #
+
+let $counter= 0;
+while ($counter < 10)
+{
+--replace_result $DAEMONEXAMPLE DAEMONEXAMPLE
+  eval INSTALL PLUGIN daemon_example SONAME '$DAEMONEXAMPLE';
+  UNINSTALL PLUGIN daemon_example;
+  inc $counter;
+}

plugin/daemon_example/daemon_example.cc

@@ -46,7 +46,6 @@ pthread_handler_t mysql_heartbeat(void *p)
   DBUG_ENTER("mysql_heartbeat");
   struct mysql_heartbeat_context *con= (struct mysql_heartbeat_context *)p;
   char buffer[HEART_STRING_BUFFER];
-  unsigned int x= 0;
   time_t result;
   struct tm tm_tmp;
 
@@ -65,7 +64,6 @@ pthread_handler_t mysql_heartbeat(void *p)
                 tm_tmp.tm_min,
                 tm_tmp.tm_sec);
     my_write(con->heartbeat_file, (uchar*) buffer, strlen(buffer), MYF(0));
-    x++;
   }
 
   DBUG_RETURN(0);
@@ -160,6 +158,7 @@ static int daemon_example_plugin_deinit(void *p)
     (struct mysql_heartbeat_context *)plugin->data;
   time_t result= time(NULL);
   struct tm tm_tmp;
+  void *dummy_retval;
 
   pthread_cancel(con->heartbeat_thread);
 
@@ -173,6 +172,13 @@ static int daemon_example_plugin_deinit(void *p)
               tm_tmp.tm_min,
               tm_tmp.tm_sec);
   my_write(con->heartbeat_file, (uchar*) buffer, strlen(buffer), MYF(0));
+
+  /*
+    Need to wait for the hearbeat thread to terminate before closing
+    the file it writes to and freeing the memory it uses
+  */
+  pthread_join(con->heartbeat_thread, &dummy_retval);
+
   my_close(con->heartbeat_file, MYF(0));
 
   my_free(con);