Re: [linux-pm] [RFC] ACPI vs device ordering on resume

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > > > So it looks like we need this sequence:
> > > > 
> > > > enable_nonboot_cpus() /* INIT */
> > > > finish()	/* _WAK */
> > > > device_resume()
> > > 
> > > Can somebody remind me about this immediately after 2.6.19?
> > 
> > Remind. But note that freezer is not yet SMP safe... Rafael is working
> > on that.
> 
> Yup.
> 
> BTW, have you looked at the last version of the patch for the handling of
> stopped tasks (appended just in case, full discussion at:
> http://lists.osdl.org/pipermail/linux-pm/2006-November/004214.html)?

Well, I took a look.. and decided I'd like to find the place in kernel
where I can add try_to_freeze() and fix the TASK_STOPPED processes. I
hope such place exists.
								Pavel 

> 
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> ---
>  kernel/power/process.c |   36 ++++++++++++++++++++++++++++++------
>  kernel/signal.c        |    2 +-
>  2 files changed, 31 insertions(+), 7 deletions(-)
> 
> Index: linux-2.6.19-rc6-mm2/kernel/power/process.c
> ===================================================================
> --- linux-2.6.19-rc6-mm2.orig/kernel/power/process.c
> +++ linux-2.6.19-rc6-mm2/kernel/power/process.c
> @@ -28,8 +28,7 @@ static inline int freezeable(struct task
>  	if ((p == current) || 
>  	    (p->flags & PF_NOFREEZE) ||
>  	    (p->exit_state == EXIT_ZOMBIE) ||
> -	    (p->exit_state == EXIT_DEAD) ||
> -	    (p->state == TASK_STOPPED))
> +	    (p->exit_state == EXIT_DEAD))
>  		return 0;
>  	return 1;
>  }
> @@ -81,6 +80,11 @@ static void cancel_freezing(struct task_
>  	}
>  }
>  
> +static inline int stopped_and_freezing(struct task_struct *p)
> +{
> +	return p->state == TASK_STOPPED && freezing(p);
> +}
> +
>  static inline int is_user_space(struct task_struct *p)
>  {
>  	return p->mm && !(p->flags & PF_BORROWED_MM);
> @@ -103,9 +107,11 @@ static unsigned int try_to_freeze_tasks(
>  			if (frozen(p))
>  				continue;
>  
> -			if (p->state == TASK_TRACED &&
> -			    (frozen(p->parent) ||
> -			     p->parent->state == TASK_STOPPED)) {
> +			if (stopped_and_freezing(p))
> +				continue;
> +
> +			if (p->state == TASK_TRACED && (frozen(p->parent) ||
> +			    stopped_and_freezing(p->parent))) {
>  				cancel_freezing(p);
>  				continue;
>  			}
> @@ -149,7 +155,8 @@ static unsigned int try_to_freeze_tasks(
>  			if (is_user_space(p) == !freeze_user_space)
>  				continue;
>  
> -			if (freezeable(p) && !frozen(p))
> +			if (freezeable(p) && !frozen(p) &&
> +			    p->state != TASK_STOPPED && p->state != TASK_TRACED)
>  				printk(KERN_ERR " %s\n", p->comm);
>  
>  			cancel_freezing(p);
> @@ -185,6 +192,18 @@ int freeze_processes(void)
>  	return 0;
>  }
>  
> +static void release_stopped_tasks(void)
> +{
> +	struct task_struct *g, *p;
> +
> +	read_lock(&tasklist_lock);
> +	do_each_thread(g, p) {
> +		if (stopped_and_freezing(p))
> +			cancel_freezing(p);
> +	} while_each_thread(g, p);
> +	read_unlock(&tasklist_lock);
> +}
> +
>  static void thaw_tasks(int thaw_user_space)
>  {
>  	struct task_struct *g, *p;
> @@ -197,6 +216,10 @@ static void thaw_tasks(int thaw_user_spa
>  		if (is_user_space(p) == !thaw_user_space)
>  			continue;
>  
> +		if (!frozen(p) &&
> +		    (p->state == TASK_STOPPED || p->state == TASK_TRACED))
> +			continue;
> +
>  		if (!thaw_process(p))
>  			printk(KERN_WARNING " Strange, %s not stopped\n",
>  				p->comm );
> @@ -207,6 +230,7 @@ static void thaw_tasks(int thaw_user_spa
>  void thaw_processes(void)
>  {
>  	printk("Restarting tasks ... ");
> +	release_stopped_tasks();
>  	thaw_tasks(FREEZER_KERNEL_THREADS);
>  	thaw_tasks(FREEZER_USER_SPACE);
>  	schedule();
> Index: linux-2.6.19-rc6-mm2/kernel/signal.c
> ===================================================================
> --- linux-2.6.19-rc6-mm2.orig/kernel/signal.c
> +++ linux-2.6.19-rc6-mm2/kernel/signal.c
> @@ -1937,9 +1937,9 @@ int get_signal_to_deliver(siginfo_t *inf
>  	sigset_t *mask = &current->blocked;
>  	int signr = 0;
>  
> +relock:
>  	try_to_freeze();
>  
> -relock:
>  	spin_lock_irq(&current->sighand->siglock);
>  	for (;;) {
>  		struct k_sigaction *ka;

-- 
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(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html