DISABLE AND ENABLED DURING DDL OPERATION
PROBLEM: Same thread trying to acquire the same mutex
second time leads to hang/server crash.
While [un]installing audit_log plugin
a thread acquires the LOCK_plugin mutex
and after successful initialization tries
to write in mysql.plugin table. It holds
this mutex for a long time. If some how
plugin table is corrupted then a write to
plugin table will throw an error, thread try
to log this error in the audit_log plugin,
doing so it tries to acquire the mutex
again and results is server hang/crash.
SOLUTION: Releasing the LOCK_plugin mutex before
writing in mysql.plugin table. We dont
need to hold this mutex as thread already
acquired a TL_WRITE lock on mysql.plugin
table.