Commit 95bfde3d authored by thek@adventure.(none)'s avatar thek@adventure.(none)
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Bug #32436 KILL QUERY completely deadlocks mysqld 

Sending several "KILL QUERY" statements to target a connection running
"SELECT SLEEP" could freeze the server.

The locking order in Item_func_sleep was wrong and this could lead to a
dead lock.

This patch solves the issue by resolving the locking order properly.
parent 1794242b

sql/item_func.cc

+1 −2
Original line number Diff line number Diff line
@@ -3732,13 +3732,12 @@ longlong Item_func_sleep::val_int() 
      break;

    error= 0;

  }



  pthread_mutex_unlock(&LOCK_user_locks);

  pthread_mutex_lock(&thd->mysys_var->mutex);

  thd->mysys_var->current_mutex= 0;

  thd->mysys_var->current_cond=  0;

  pthread_mutex_unlock(&thd->mysys_var->mutex);



  pthread_mutex_unlock(&LOCK_user_locks);

  pthread_cond_destroy(&cond);



  return test(!error); 		// Return 1 killed