Re: [PATCH -mm] swsusp: userland interface (rev 2)

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > This patch introduces a user space interface for swsusp.
> 
> How will we know if/when this feature is ready for mainline?  What criteria
> can we use to judge that?

It was stable for me last time I tested. I do not think it needs
longer -mm testing than usual patches.

> Will you be developing and long-term maintaining the userspace tools?  Is
> it your expectation/hope that distros will migrate onto using them?
> etc.

It looks like I'll do it, or Rafael can have it as an original
author. They are currently hosted at sf.net/projects/suspend. SuSE is
very likely to use them for 10.2 or so -- we want to provide nice
splashscreen so that users are not scared :-), we would like to do
encryption/compression too, etc.

> > +static int snapshot_ioctl(struct inode *inode, struct file *filp,
> > +                          unsigned int cmd, unsigned long arg)
> > +{
> >
> > ...
> >
> > +	case SNAPSHOT_ATOMIC_RESTORE:
> > +		if (data->mode != O_WRONLY || !data->frozen ||
> > +		    !snapshot_image_loaded(&data->handle)) {
> > +			error = -EPERM;
> > +			break;
> > +		}
> > +		down(&pm_sem);
> > +		pm_prepare_console();
> > +		error = device_suspend(PMSG_FREEZE);
> > +		if (!error) {
> > +			mb();
> > +			error = swsusp_resume();
> > +			device_resume();
> > +		}
> 
> whee, what does the mystery barrier do?  It'd be nice to comment this
> (please always comment open-coded barriers).

It is probably relic from very early code, should not be needed, but
everyone is scared of removing it.
								Pavel
-- 
Thanks, Sharp!