[PATCH] power: suspend: Add suspend timeout handler

[<josephjang@google.com>]

Thank you Rafael's promptly response.

> On Fri, Oct 16, 2020 at 5:51 AM Joseph Jang <josephjang@google.com> wrote:
> >
> > From: josephjang <josephjang@google.com>
> >
> > Add suspend timeout handler to prevent device stuck during suspend/
> > resume process. Suspend timeout handler will dump disk sleep task
> > at first round timeout and trigger kernel panic at second round timeout.
> > The default timer for each round is 30 seconds.
> >
> > Note: Can use following command to simulate suspend hang for testing.
> >     adb shell echo 1 > /sys/power/pm_hang
> >     adb shell echo mem > /sys/power/state
> > Signed-off-by: josephjang <josephjang@google.com>
> > ---
> >  include/linux/console.h |   1 +
> >  kernel/power/Kconfig    |   9 +++
> >  kernel/power/main.c     |  66 ++++++++++++++++
> >  kernel/power/suspend.c  | 162 ++++++++++++++++++++++++++++++++++++++++
> >  kernel/printk/printk.c  |   5 ++
> >  5 files changed, 243 insertions(+)
> >
> > diff --git a/include/linux/console.h b/include/linux/console.h
> > index 0670d3491e0e..ac468c602c0b 100644
> > --- a/include/linux/console.h
> > +++ b/include/linux/console.h
> > @@ -192,6 +192,7 @@ static inline void console_sysfs_notify(void)
> >  { }
> >  #endif
> >  extern bool console_suspend_enabled;
> > +extern int is_console_suspended(void);
> >
> >  /* Suspend and resume console messages over PM events */
> >  extern void suspend_console(void);
> > diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
> > index a7320f07689d..52b7a181b6d8 100644
> > --- a/kernel/power/Kconfig
> > +++ b/kernel/power/Kconfig
> > @@ -207,6 +207,15 @@ config PM_SLEEP_DEBUG
> >         def_bool y
> >         depends on PM_DEBUG && PM_SLEEP
> >
> > +config PM_SLEEP_MONITOR
> > +       bool "Linux kernel suspend/resume process monitor"
> > +       depends on PM_SLEEP
> > +       help
> > +       This option will enable suspend/resume monitor to prevent device
> > +       stuck during suspend/resume process. Suspend timeout handler  
> will
> > +       dump disk sleep task at first round timeout and trigger kernel  
> panic
> > +       at second round timeout. The default timer for each round is 30  
> seconds.
> > +

> The facility associated with the Kconfig entry right below is supposed
> to do exactly the same thing.

> What's the reason to add another one?  What is missing?



> >  config DPM_WATCHDOG
> >         bool "Device suspend/resume watchdog"
> >         depends on PM_DEBUG && PSTORE && EXPERT

Because we found some suspend hand issue that cannot be detected by
"CONFIG_DPM_WATCHDOG" (which is focus on device PM).
Our suspend timeout monitor can cover PM core and Device PM hang issues.

Thank you,
Joseph.