On Fri, May 25, 2018 at 11:46 AM, Sebastian Andrzej Siewior
<bige...@linutronix.de> wrote:
> From: Thomas Gleixner <t...@linutronix.de>
>
> timekeeping suspend/resume calls read_persistent_clock() which takes
> rtc_lock. That results in might sleep warnings because at that point
> we run with interrupts disabled.
>
> We cannot convert rtc_lock to a raw spinlock as that would trigger
> other might sleep warnings.
>
> As a workaround we disable the might sleep warnings by setting
> system_state to SYSTEM_SUSPEND before calling sysdev_suspend() and
> restoring it to SYSTEM_RUNNING afer sysdev_resume().
>
> Signed-off-by: Thomas Gleixner <t...@linutronix.de>
> [bigeasy: cover s2idle]
> Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
> ---
> include/linux/kernel.h | 1 +
> kernel/power/hibernate.c | 7 +++++++
> kernel/power/suspend.c | 6 ++++++
> 3 files changed, 14 insertions(+)
>
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index 6a1eb0b0aad9..7aed92624531 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -542,6 +542,7 @@ extern enum system_states {
> SYSTEM_HALT,
> SYSTEM_POWER_OFF,
> SYSTEM_RESTART,
> + SYSTEM_SUSPEND,
> } system_state;
>
> /* This cannot be an enum because some may be used in assembly source. */
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index 5454cc639a8d..9c85c7822383 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -287,6 +287,8 @@ static int create_image(int platform_mode)
>
> local_irq_disable();
>
> + system_state = SYSTEM_SUSPEND;
> +
> error = syscore_suspend();
> if (error) {
> pr_err("Some system devices failed to power down, aborting
> hibernation\n");
> @@ -317,6 +319,7 @@ static int create_image(int platform_mode)
> syscore_resume();
>
> Enable_irqs:
> + system_state = SYSTEM_RUNNING;
> local_irq_enable();
>
> Enable_cpus:
> @@ -445,6 +448,7 @@ static int resume_target_kernel(bool platform_mode)
> goto Enable_cpus;
>
> local_irq_disable();
> + system_state = SYSTEM_SUSPEND;
>
> error = syscore_suspend();
> if (error)
> @@ -478,6 +482,7 @@ static int resume_target_kernel(bool platform_mode)
> syscore_resume();
>
> Enable_irqs:
> + system_state = SYSTEM_RUNNING;
> local_irq_enable();
>
> Enable_cpus:
> @@ -563,6 +568,7 @@ int hibernation_platform_enter(void)
> goto Enable_cpus;
>
> local_irq_disable();
> + system_state = SYSTEM_SUSPEND;
> syscore_suspend();
> if (pm_wakeup_pending()) {
> error = -EAGAIN;
> @@ -575,6 +581,7 @@ int hibernation_platform_enter(void)
>
> Power_up:
> syscore_resume();
> + system_state = SYSTEM_RUNNING;
> local_irq_enable();
>
> Enable_cpus:
> diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
> index 4c10be0f4843..9108a99878bf 100644
> --- a/kernel/power/suspend.c
> +++ b/kernel/power/suspend.c
> @@ -110,6 +110,7 @@ static void s2idle_loop(void)
> {
> pm_pr_dbg("suspend-to-idle\n");
>
> + system_state = SYSTEM_SUSPEND;
And here's the ambiguity.
For the other sleep variants SYSTEM_SUSPEND means "all devices have
been suspended, interrupts are off and there's one CPU active".
Here, device suspend has not even completed entirely.
I guess you could set system_state to SYSTEM_SUSPEND right before
calling timekeeping_suspend() in tick_freeze() and then back to
SYSTEM_RUNNING after timekeeping_resume() has returned in
tick_unfreeze(), but talk to Thomas about that first. :-)
