lkml.org 
[lkml]   [2012]   [Feb]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] PM/Freezer: Thaw only kernel threads if freezing of kernel threads fails
Date
On Wednesday, February 01, 2012, Tejun Heo wrote:
> On Thu, Feb 02, 2012 at 04:01:12AM +0530, Srivatsa S. Bhat wrote:
> > If freezing of kernel threads fails, we are expected to automatically thaw
> > tasks in the error recovery path. However, at times, we encounter situations
> > in which we would like the automatic error recovery path to thaw only the
> > kernel threads, because we want to be able to do some more cleanup before
> > we thaw userspace. Something like:
> >
> > error = freeze_kernel_threads();
> > if (error) {
> > /* Do some cleanup */
> >
> > /* Only then thaw userspace tasks*/
> > thaw_processes();
> > }
> >
> > An example of such a situation is where we freeze/thaw filesystems during
> > suspend/hibernation. There, if freezing of kernel threads fails, we would
> > like to thaw the frozen filesystems before thawing the userspace tasks.
> >
> > So, modify freeze_kernel_threads() to thaw only kernel threads in case of
> > freezing failure.
> >
> > Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
>
> Acked-by: Tejun Heo <tj@kernel.org>
>
> with nits below,
>
> > ---
> >
> > kernel/power/power.h | 26 ++++++++++++++++++++++++--
> > kernel/power/process.c | 7 +++++--
> > 2 files changed, 29 insertions(+), 4 deletions(-)
> >
> > diff --git a/kernel/power/power.h b/kernel/power/power.h
> > index 0c4defe..cf41c03 100644
> > --- a/kernel/power/power.h
> > +++ b/kernel/power/power.h
> > @@ -231,8 +231,30 @@ extern int pm_test_level;
> > #ifdef CONFIG_SUSPEND_FREEZER
> > static inline int suspend_freeze_processes(void)
> > {
> > - int error = freeze_processes();
> > - return error ? : freeze_kernel_threads();
> > + int error;
> > +
> > + error = freeze_processes();
> > +
> > + /*
> > + * freeze_processes() automatically thaws
> > + * every task if freezing fails. So we need
> > + * not do anything extra upon error.
> > + */
> > + if (error)
> > + goto Finish;
> > +
> > + error = freeze_kernel_threads();
> > +
> > + /*
> > + * freeze_kernel_threads() thaws only kernel
> > + * threads upon freezing failure. So we have
> > + * to thaw the userspace tasks ourselves.
> > + */
> > + if (error)
> > + thaw_processes();
> > +
> > + Finish:
> > + return error;
>
> Heh, the original ?: code was scary.

C'mon. ;-)

> That said, IMHO, the above seems
> a bit too verbose. Functions usually shouldn't have side effects on
> failure and the above code is usual in that sense and it would be nice
> to mention the reformatting (from cryptic to sane) in the commit log.
> Also, how many columns are you flowing the text to? It seems quite
> narrower than they usually should be.

I agree.

Srivatsa, care to resubmit?

Rafael


\
 
 \ /
  Last update: 2012-02-01 23:47    [from the cache]
©2003-2011 Jasper Spaans