On Friday, May 25, 2018 5:54:41 PM CEST Sebastian Andrzej Siewior 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(). There is no lock
> contention because hibernate / suspend to RAM is single-CPU at this
> point.
>
> In s2idle's case the system_state is set to SYSTEM_SUSPEND before
> timekeeping_suspend() which is invoked by the last CPU. In the resume
> case it set back to SYSTEM_RUNNING after timekeeping_resume() which is
> invoked by the first CPU in the resume case. The other CPUs will block
> on tick_freeze_lock.
>
> Signed-off-by: Thomas Gleixner <t...@linutronix.de>
> [bigeasy: cover s2idle in tick_freeze() / tick_unfreeze()]
> Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
> ---
> v1…v2: Moved the s2idle case into tick_freeze()/unfreeze() as suggested
> by Rafael (tglx was okay with this).
>
> include/linux/kernel.h | 1 +
> kernel/power/hibernate.c | 7 +++++++
> kernel/power/suspend.c | 4 ++++
> kernel/time/tick-common.c | 2 ++
> 4 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..5149c77506b3 100644
> --- a/kernel/power/suspend.c
> +++ b/kernel/power/suspend.c
> @@ -428,6 +428,8 @@ static int suspend_enter(suspend_state_t state, bool
> *wakeup)
> arch_suspend_disable_irqs();
> BUG_ON(!irqs_disabled());
>
> + system_state = SYSTEM_SUSPEND;
> +
> error = syscore_suspend();
> if (!error) {
> *wakeup = pm_wakeup_pending();
> @@ -443,6 +445,8 @@ static int suspend_enter(suspend_state_t state, bool
> *wakeup)
> syscore_resume();
> }
>
> + system_state = SYSTEM_RUNNING;
> +
> arch_suspend_enable_irqs();
> BUG_ON(irqs_disabled());
>
> diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
> index 49edc1c4f3e6..14de3727b18e 100644
> --- a/kernel/time/tick-common.c
> +++ b/kernel/time/tick-common.c
> @@ -490,6 +490,7 @@ void tick_freeze(void)
> if (tick_freeze_depth == num_online_cpus()) {
> trace_suspend_resume(TPS("timekeeping_freeze"),
> smp_processor_id(), true);
> + system_state = SYSTEM_SUSPEND;
> timekeeping_suspend();
> } else {
> tick_suspend_local();
> @@ -513,6 +514,7 @@ void tick_unfreeze(void)
>
> if (tick_freeze_depth == num_online_cpus()) {
> timekeeping_resume();
> + system_state = SYSTEM_RUNNING;
> trace_suspend_resume(TPS("timekeeping_freeze"),
> smp_processor_id(), false);
> } else {
>
Applied along with the rest of the series, thanks!
