Re: [PATCH] reboot: Backup orderly_poweroff

[Keerthy]

On Monday 11 January 2016 08:25 PM, Josh Triplett wrote:
> On Mon, Jan 11, 2016 at 03:53:24PM +0530, Keerthy wrote:
> > orderly_poweroff is triggered when a graceful shutdown
> > of system is desired. This may be used in many critical states of the
> > kernel such as when subsystems detects conditions such as critical
> > temperature conditions. However, in certain conditions in system
> > boot up sequences like those in the middle of driver probes being
> > initiated, userspace will be unable to power off the system in a clean
> > manner and leaves the system in a critical state. In cases like these,
> > the /sbin/poweroff will return success (having forked off to attempt
> > powering off the system. However, the system overall will fail to
> > completely poweroff (since other modules will be probed) and the system
> > is still functional with no userspace (since that would have shut itself
> > off).
> >
> > However, there is no clean way of detecting such failure of userspace
> > powering off the system. In such scenarios, it is necessary for a backup
> > workqueue to be able to force a shutdown of the system when orderly
> > shutdown is not successful after a configurable time period.
>
> One issue below, inline.
>
> > Signed-off-by: Keerthy <j-keerthy@xxxxxx>
> > Suggested-by: Eduardo Valentin <edubezval@xxxxxxxxx>
> > Reported-by: Nishanth Menon <nm@xxxxxx>
> > ---
> > Links to previous discussion can be found here:
> >
> > http://www.spinics.net/lists/linux-omap/msg124925.html
> >
> > Boot tested on DRA7.
> >
> >   arch/Kconfig    |  7 +++++++
> >   kernel/reboot.c | 23 ++++++++++++++++++-----
> >   2 files changed, 25 insertions(+), 5 deletions(-)
> >
> > Index: linux/arch/Kconfig
> > ===================================================================
> > --- linux.orig/arch/Kconfig	2016-01-11 15:26:07.732173131 +0530
> > +++ linux/arch/Kconfig	2016-01-11 15:26:07.728173205 +0530
> > @@ -37,6 +37,18 @@
> >   	def_bool y
> >   	depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
> >
> > +config SHUTDOWN_BACKUP_DELAY_MS
> > +	int "Backup shutdown delay in milli-seconds"
> > +	default 0
>
> With no dependencies, as far as I can tell this will always get defined
> with a value, defaulting to 0.  (I don't know of any special cases in
> Kconfig for an int value of 0.)  Thus, in the code below...

Yes. I will fix this and post a new version. Thanks for the review.

Regards,
Keerthy
> > --- linux.orig/kernel/reboot.c	2016-01-11 15:26:07.732173131 +0530
> > +++ linux/kernel/reboot.c	2016-01-11 15:38:33.502341511 +0530
> > @@ -424,6 +424,38 @@
> >   	return ret;
> >   }
> >
> > +#ifdef CONFIG_SHUTDOWN_BACKUP_DELAY_MS
>
> ...this should use #if, not #ifdef.  Otherwise this code will get
> compiled into every kernel.
>
> - Josh Triplett