Re: [PATCH] power: suspend: Add suspend timeout handler

[Rafael J. Wysocki]

On Fri, Oct 16, 2020 at 5:51 AM Joseph Jang <josephjang@xxxxxxxxxx> wrote:
>
> From: josephjang <josephjang@xxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> ---
>  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