linux-kernel - Re: [PATCH 1/2] lguest: move process freezing before pending signals check

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Date:	Wed, 12 Oct 2011 08:55:04 +0200
From:	Michal Hocko <mhocko@...e.cz>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	David Rientjes <rientjes@...gle.com>,
	Konstantin Khlebnikov <khlebnikov@...nvz.org>,
	Oleg Nesterov <oleg@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Tejun Heo <htejun@...il.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/2] lguest: move process freezing before pending signals
 check

Hi Rusty,
what is the current state of this patch? Are you planning to push it for
3.2?

Thanks

On Tue 27-09-11 08:56:03, Michal Hocko wrote:
> run_guest tries to freeze the current process after it has handled
> pending interrupts and before it calls lguest_arch_run_guest.
> This doesn't work nicely if the task has been killed while being frozen
> and when we want to handle that signal as soon as possible.
> Let's move try_to_freeze before we check for pending signal so that we
> can get out of the loop as soon as possible.
> 
> Signed-off-by: Michal Hocko <mhocko@...e.cz>
> Acked-by: Rusty Russell <rusty@...tcorp.com.au>
> ---
>  drivers/lguest/core.c |   14 +++++++-------
>  1 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
> index 2535933..e7dda91 100644
> --- a/drivers/lguest/core.c
> +++ b/drivers/lguest/core.c
> @@ -232,6 +232,13 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
>  			}
>  		}
>  
> +		/*
> +		 * All long-lived kernel loops need to check with this horrible
> +		 * thing called the freezer.  If the Host is trying to suspend,
> +		 * it stops us.
> +		 */
> +		try_to_freeze();
> +
>  		/* Check for signals */
>  		if (signal_pending(current))
>  			return -ERESTARTSYS;
> @@ -246,13 +253,6 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
>  			try_deliver_interrupt(cpu, irq, more);
>  
>  		/*
> -		 * All long-lived kernel loops need to check with this horrible
> -		 * thing called the freezer.  If the Host is trying to suspend,
> -		 * it stops us.
> -		 */
> -		try_to_freeze();
> -
> -		/*
>  		 * Just make absolutely sure the Guest is still alive.  One of
>  		 * those hypercalls could have been fatal, for example.
>  		 */
> -- 
> 1.7.5.4
> 

-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic
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