Re: [PATCH] swsusp: Use platform mode by default

[Qi Yong <qiyong@fc-cn.com>]

On Wed, Oct 17, 2007 at 10:46:12AM +0800, Qi Yong wrote:
> On 12/05/2007, Linus Torvalds <torvalds@linux-foundation.org> wrote:
> >
> >
> > On Fri, 11 May 2007, Rafael J. Wysocki wrote:
> > >
> > > We're working on fixing the breakage, but currently it's difficult, because
> > > none of my testboxes has problems with the 'platform' hibernation and I
> > > cannot reproduce the reported issues.
> >
> > The rule for anything ACPI-related has been: no regressions.
> >
> > It doesn't matter if something fixes 10 boxes, if it breaks a single one,
> > it's going to get reverted.
> >
> > We had much too much of the "two steps forward, one step back" dance with
> > ACPI a few years ago, which is the reason that rule got installed (and
> > which is why it's ACPI-only: in some other subsystems we accept the fact
> > that sometimes we don't know how to fix some hardware issue, but the new
> > situation is at least better than the old one).
> >
> > I agree that it can be aggravating to know that you can fix a problem for
> > some people, but then being limited by the fact that it breaks for others.
> > But beign able to *rely* on something that used to work is just too
> > important, and with ACPI, you can never make a good judgement of which way
> > works better (since it really just depends on some random firmware issues
> > that we have zero visibility into).
> >
> > Also, quite often, it may *seem* like something fixes more boxes than it
> > breaks, but it's because people report *breakage* only, and then a few
> > months later it turns out that it's exactly the other way around: now it's
> > a hundred people who report breakage with the *new* code, and the reason
> > people thought it fixed more than it broke was that the people for whom
> > the old code worked fine obviously never reported it!
> >
> > So this is why "a single regression is considered more important than ten
> > fixes" - because a single regressionr report tends to actually be just the
> > first indication of a lot of people who simply haven't tested the new code
> > yet! People for whom the old code is broken are more likely to test new
> > things.
> >
> > So I'd just suggest changing the default back to PM_DISK_SHUTDOWN (but
> > leave the "pm_ops->enter" testing in place - ie not reverting the other
> > commits in the series).
> >
> > The patch would look something like this. Coywolf, does this fix it for
> > you?
> >
> 
> Yes, it fixes my problem.
> 
> (Sorry for this long delayed report. I didn't get the chance to test
> and reboot my box.)
> 
> This quick test explains me the problem that we should not set
> hibernation_mode to HIBERNATION_PLATFORM if it is not !ops". I will
> post a formal patch later.
> 
> diff --git a/kernel/power/disk.c b/kernel/power/disk.c
> index eb72255..8e52553 100644
> --- a/kernel/power/disk.c
> +++ b/kernel/power/disk.c
> @@ -62,7 +62,7 @@ void hibernation_set_ops(struct hibernation_ops *ops)
>         mutex_lock(&pm_mutex);
>         hibernation_ops = ops;
>         if (ops)
> -               hibernation_mode = HIBERNATION_PLATFORM;
> +               ;
>         else if (hibernation_mode == HIBERNATION_PLATFORM)
>                 hibernation_mode = HIBERNATION_SHUTDOWN;

please apply.

Signed-off-by: Qi Yong <qiyong@fc-cn.com>
---

diff --git a/kernel/power/disk.c b/kernel/power/disk.c
index eb72255..95b66ee 100644
--- a/kernel/power/disk.c
+++ b/kernel/power/disk.c
@@ -61,9 +61,11 @@ void hibernation_set_ops(struct hibernation_ops *ops)
 	}
 	mutex_lock(&pm_mutex);
 	hibernation_ops = ops;
-	if (ops)
-		hibernation_mode = HIBERNATION_PLATFORM;
-	else if (hibernation_mode == HIBERNATION_PLATFORM)
+
+	/*
+	 * Turn off HIBERNATION_PLATFORM if we no longer have any platform ops.
+	 */
+	if (!ops && hibernation_mode == HIBERNATION_PLATFORM)
 		hibernation_mode = HIBERNATION_SHUTDOWN;
 
 	mutex_unlock(&pm_mutex);


> 
> >                         Linus
> >
> > ---
> >  kernel/power/disk.c |    6 +++---
> >  1 files changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/kernel/power/disk.c b/kernel/power/disk.c
> > index b5f0543..f6aa06e 100644
> > --- a/kernel/power/disk.c
> > +++ b/kernel/power/disk.c
> > @@ -60,9 +60,9 @@ void hibernation_set_ops(struct hibernation_ops *ops)
> >         }
> >         mutex_lock(&pm_mutex);
> >         hibernation_ops = ops;
> > -       if (ops)
> > -               hibernation_mode = HIBERNATION_PLATFORM;
> > -       else if (hibernation_mode == HIBERNATION_PLATFORM)
> > +
> > +       /* Turn off HIBERNATION_PLATFORM if we no longer have any platform ops */
> > +       if (!ops && hibernation_mode == HIBERNATION_PLATFORM)
> >                 hibernation_mode = HIBERNATION_SHUTDOWN;
> >
> >         mutex_unlock(&pm_mutex);
> >
> 
> 
> -- 
> Qi Yong
> -
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