linux-kernel - Re: [PATCH] ACPI / cpuidle: Remove acpi_idle

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Date:	Mon, 14 Nov 2011 16:34:05 +0530
From:	Deepthi Dharwar <deepthi@...ux.vnet.ibm.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
CC:	Len Brown <lenb@...nel.org>, Ferenc Wagner <wferi@...f.hu>,
	"Tomas M." <tmezzadra@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	g.trinabh@...il.com, j-pihet@...com, khilman@...com,
	arjan@...ux.intel.com, len.brown@...el.com,
	Arjan van de Ven <arjan@...radead.org>,
	Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [PATCH] ACPI / cpuidle: Remove acpi_idle_suspend (to fix suspend
 regression)

Thanks a lot Ferenc and Tomas for reporting the problem and testing the fix.
Thanks a ton Rafael for plugging the bug with an amazing turn around time !!

-- Deepthi

On Sunday 13 November 2011 03:47 AM, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@...k.pl>
> 
> After commit e978aa7d7d57d04eb5f88a7507c4fb98577def77 (cpuidle: Move
> dev->last_residency update to driver enter routine; remove
> dev->last_state) setting acpi_idle_suspend to 1 by
> acpi_processor_suspend() causes the ACPI cpuidle routines to return
> error codes continuously, which in turn causes cpuidle to lock up
> (hard).  However, acpi_idle_suspend doesn't appear to be useful for
> any particular purpose (it's racy and doesn't really provide any real
> protection), so it can be removed, which makes the problem go away.
> 
> Reported-and-tested-by: Tomas M. <tmezzadra@...il.com>
> Reported-and-tested-by: Ferenc Wagner <wferi@...f.hu>
> Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> ---
>  drivers/acpi/processor_idle.c |   29 -----------------------------
>  1 file changed, 29 deletions(-)
> 
> Index: linux/drivers/acpi/processor_idle.c
> ===================================================================
> --- linux.orig/drivers/acpi/processor_idle.c
> +++ linux/drivers/acpi/processor_idle.c
> @@ -224,7 +224,6 @@ static void lapic_timer_state_broadcast(
>  /*
>   * Suspend / resume control
>   */
> -static int acpi_idle_suspend;
>  static u32 saved_bm_rld;
> 
>  static void acpi_idle_bm_rld_save(void)
> @@ -243,21 +242,13 @@ static void acpi_idle_bm_rld_restore(voi
> 
>  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;
>  }
> 
> @@ -763,13 +754,6 @@ static int acpi_idle_enter_c1(struct cpu
> 
>  	local_irq_disable();
> 
> -	/* Do not access any ACPI IO ports in suspend path */
> -	if (acpi_idle_suspend) {
> -		local_irq_enable();
> -		cpu_relax();
> -		return -EINVAL;
> -	}
> -
>  	lapic_timer_state_broadcast(pr, cx, 1);
>  	kt1 = ktime_get_real();
>  	acpi_idle_do_entry(cx);
> @@ -810,13 +794,6 @@ static int acpi_idle_enter_simple(struct
> 
>  	local_irq_disable();
> 
> -	if (acpi_idle_suspend) {
> -		local_irq_enable();
> -		cpu_relax();
> -		return -EINVAL;
> -	}
> -
> -
>  	if (cx->entry_method != ACPI_CSTATE_FFH) {
>  		current_thread_info()->status &= ~TS_POLLING;
>  		/*
> @@ -895,12 +872,6 @@ static int acpi_idle_enter_bm(struct cpu
>  	if (unlikely(!pr))
>  		return -EINVAL;
> 
> -
> -	if (acpi_idle_suspend) {
> -		cpu_relax();
> -		return -EINVAL;
> -	}
> -
>  	if (!cx->bm_sts_skip && acpi_idle_bm_check()) {
>  		if (drv->safe_state_index >= 0) {
>  			return drv->states[drv->safe_state_index].enter(dev,
> 
> --
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