Re: [PATCH] rcu_sched_grace_period: kill the bogus flush_signals()

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Sun, May 03, 2009 at 11:11:18PM +0200, Oleg Nesterov wrote:
> As a kernel thread, rcu_sched_grace_period() runs with all signals ignored.
> It can never receive a signal even if it sleeps in TASK_INTERRUPTIBLE, it
> needs the explicit allow_signal() to be visible for signals.

Good point!!!

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> 
> --- PTRACE/kernel/rcupreempt.c~	2009-04-09 00:39:10.000000000 +0200
> +++ PTRACE/kernel/rcupreempt.c	2009-05-03 02:17:11.000000000 +0200
> @@ -1356,17 +1356,11 @@ static int rcu_sched_grace_period(void *
> 
>  		rcu_ctrlblk.sched_sleep = rcu_sched_sleeping;
>  		spin_unlock_irqrestore(&rcu_ctrlblk.schedlock, flags);
> -		ret = 0;
> +		ret = 0; /* unused */
>  		__wait_event_interruptible(rcu_ctrlblk.sched_wq,
>  			rcu_ctrlblk.sched_sleep != rcu_sched_sleeping,
>  			ret);
> 
> -		/*
> -		 * Signals would prevent us from sleeping, and we cannot
> -		 * do much with them in any case.  So flush them.
> -		 */
> -		if (ret)
> -			flush_signals(current);
>  		couldsleepnext = 0;
> 
>  	} while (!kthread_should_stop());
>