[PATCH] Fix bug in RCU torture test

While doing some test of RCU torture module, I hit a OOPS in rcu_do_batch,
which was trying to processes callback of a module that was just removed.
This is because we weren't waiting long enough for all callbacks to fire.

Signed-off-by: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Acked-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/rcutorture.c

@@ -409,9 +409,8 @@ rcu_torture_cleanup(void)
 	stats_task = NULL;
 
 	/* Wait for all RCU callbacks to fire.  */
+	rcu_barrier();
 
-	for (i = 0; i < RCU_TORTURE_PIPE_LEN; i++)
-		synchronize_rcu();
 	rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
 	printk(KERN_ALERT TORTURE_FLAG
 	       "--- End of test: %s\n",