Re: boot hang on commit "PM / ACPI: Fix suspend/resume regression caused by cpuidle cleanup."

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Monday, June 25, 2012, Deepthi Dharwar wrote:
> From: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
> 
> Fix suspend/resume regression caused by cpuidle cleanup.
> 
> Commit e978aa7d7d57d04eb5f88a7507c4fb98577def77 ( cpuidle: Move
> dev->last_residency update to driver enter routine; remove dev->last_state)
> was  breaking suspend on laptops, as reported in the below link
> 	- https://lkml.org/lkml/2011/11/11/164
> 
> This was fixed in commit 3439a8da16bcad6b0982ece938c9f8299bb53584
> (ACPI / cpuidle: Remove acpi_idle_suspend (to fix suspend regression)
> by removing acpi_idle_suspend flag.
> 	- https://lkml.org/lkml/2011/11/14/74
> 
> But this did fix did not work on all systems
> as Suspend/resume regression was reported on Lenovo S10-3
> recently by Dave.
> 	- https://lkml.org/lkml/2012/5/27/115
> It looked like with commit e978aa7d broke suspend and
> with commit 3439a8da resume was not working with acpi_idle driver.
> 
> This patch fixes the regression that caused this issue
> in the first place. acpi_idle_suspend flag is essential on
> some x86 systems to prevent the cpus from going to deeper C-states
> when suspend is triggered ( commit b04e7bdb984 )
> So reverting the commit 3439a8da is essential.
> 
> By default, irqs are disabled in cpu_idle arch specific call
> and re-enabled in idle state return path . During suspend,
> the acpi_idle_suspend flag is set, which
> prevents the cpus from going to deeper idle states,
> it is essential to enabling the irqs in this return path too.
> 
> To address the suspend issue,
> we were not re-enabling the interrupts while returning from
> acpi_idle_enter_bm() routine if acpi_idle_suspend flag is set.
> and this caused suspend failure.
> 
> In addition to the above, to improve the readability of the code,
> return of -ENIVAL is replaced with -EBUSY in acpi_idle_suspend
> return path. Implying that the system is currently busy when suspend
> is in progress, which prevents the cpus from entering deeper C-states.
> 
> ---
> This patch applies on 3.5-rc2
> 
> Reported-and-Tested-by: Dav Hansen <dave@linux.vnet.ibm.com>
> Tested-by: Preeti Murthy <preeti@linux.vnet.ibm.com>
> Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
> Reviewed-by: Srivatsa S Bhat <srivatsa.bhat@linux.vnet.ibm.com>
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

Looking good.  I'll give it a bit of testing and put it into linux-next for
a day or two to make sure nobody sees any more problems with it.

Thanks,
Rafael


> ---
>  drivers/acpi/processor_idle.c |   32 ++++++++++++++++++++++++++++++--
>  1 files changed, 30 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index f3decb3..47a8caa 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -224,6 +224,7 @@ static void lapic_timer_state_broadcast(struct acpi_processor *pr,
>  /*
>   * Suspend / resume control
>   */
> +static int acpi_idle_suspend;
>  static u32 saved_bm_rld;
>  
>  static void acpi_idle_bm_rld_save(void)
> @@ -242,13 +243,21 @@ static void acpi_idle_bm_rld_restore(void)
>  
>  int acpi_processor_suspend(struct acpi_device * device, pm_message_t state)
>  {
> +	if (acpi_idle_suspend == 1)
> +		return 0;
> +
>  	acpi_idle_bm_rld_save();
> +	acpi_idle_suspend = 1;
>  	return 0;
>  }
>  
>  int acpi_processor_resume(struct acpi_device * device)
>  {
> +	if (acpi_idle_suspend == 0)
> +		return 0;
> +
>  	acpi_idle_bm_rld_restore();
> +	acpi_idle_suspend = 0;
>  	return 0;
>  }
>  
> @@ -754,6 +763,12 @@ static int acpi_idle_enter_c1(struct cpuidle_device *dev,
>  
>  	local_irq_disable();
>  
> +	if (acpi_idle_suspend) {
> +		local_irq_enable();
> +		cpu_relax();
> +		return -EBUSY;
> +	}
> +
>  	lapic_timer_state_broadcast(pr, cx, 1);
>  	kt1 = ktime_get_real();
>  	acpi_idle_do_entry(cx);
> @@ -823,6 +838,12 @@ static int acpi_idle_enter_simple(struct cpuidle_device *dev,
>  
>  	local_irq_disable();
>  
> +	if (acpi_idle_suspend) {
> +		local_irq_enable();
> +		cpu_relax();
> +		return -EBUSY;
> +	}
> +
>  	if (cx->entry_method != ACPI_CSTATE_FFH) {
>  		current_thread_info()->status &= ~TS_POLLING;
>  		/*
> @@ -907,14 +928,21 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
>  						drv, drv->safe_state_index);
>  		} else {
>  			local_irq_disable();
> -			acpi_safe_halt();
> +			if (!acpi_idle_suspend)
> +				acpi_safe_halt();
>  			local_irq_enable();
> -			return -EINVAL;
> +			return -EBUSY;
>  		}
>  	}
>  
>  	local_irq_disable();
>  
> +	if (acpi_idle_suspend) {
> +		local_irq_enable();
> +		cpu_relax();
> +		return -EBUSY;
> +	}
> +
>  	if (cx->entry_method != ACPI_CSTATE_FFH) {
>  		current_thread_info()->status &= ~TS_POLLING;
>  		/*
> 
> Cheers,
> Deepthi
> 
> 
>