From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Pavel Machek <pavel@suse.cz>
Subject: Re: [ 06/23] [Suspend2] Disable usermode helper invocations when the freezer is on.
Date: Mon, 30 Jan 2006 23:05:17 +0100
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Cc: Nigel Cunningham <nigel@suspend2.net>, linux-kernel@vger.kernel.org
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Hi,

On Thursday 26 January 2006 04:45, Nigel Cunningham wrote:
> 
> Disable usermode helper invocations when the freezer is on. This avoids
> deadlocks due to hotplug events occuring while processes are frozen.
> 
> Signed-off-by: Nigel Cunningham <nigel@suspend2.net>
> 
>  kernel/kmod.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/kernel/kmod.c b/kernel/kmod.c
> index 51a8920..12afa2c 100644
> --- a/kernel/kmod.c
> +++ b/kernel/kmod.c
> @@ -36,6 +36,7 @@
>  #include <linux/mount.h>
>  #include <linux/kernel.h>
>  #include <linux/init.h>
> +#include <linux/freezer.h>
>  #include <asm/uaccess.h>
>  
>  extern int max_threads;
> @@ -249,6 +250,9 @@ int call_usermodehelper_keys(char *path,
>  	if (!khelper_wq)
>  		return -EBUSY;
>  
> +	if (freezer_is_on())
> +		return 0;
> +
>  	if (path[0] == '\0')
>  		return 0;
>  

Disabling the usermode helper while freeze_processes() is executed seems to be
a good idea to me, but I think it should be done with a mutex or something
like that.

Greetings,
Rafael
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