linux-kernel - Re: [2/5] watchdog: octeon: Handle the FROZEN hot plug notifier actions.

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Date:	Thu, 7 Apr 2016 06:19:27 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Richard Cochran <rcochran@...utronix.de>
Cc:	linux-kernel@...r.kernel.org, rt@...utronix.de,
	Wim Van Sebroeck <wim@...ana.be>,
	linux-watchdog@...r.kernel.org
Subject: Re: [2/5] watchdog: octeon: Handle the FROZEN hot plug notifier
 actions.

On Fri, Mar 18, 2016 at 10:26:08PM +0100, Richard Cochran wrote:
> When performing a suspend operation, the kernel brings all of the
> non-boot CPUs offline, calling the hot plug notifiers with the flag,
> CPU_TASKS_FROZEN, set in the action code.  Similarly, during resume,
> the CPUs are brought back online, but again the notifiers have the
> FROZEN flag set.
> 
> While some very few drivers really need to treat suspend/resume
> specially, this driver unintentionally ignores the notifications.
> 
> This patch changes the driver to disable the watchdog interrupt
> whenever the CPU goes offline, and to enable it whenever the CPU goes
> back online.  As a result, the suspended state is no longer a special
> case that leaves the watchdog active.
> 
> Cc: Wim Van Sebroeck <wim@...ana.be>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc: linux-watchdog@...r.kernel.org
> Signed-off-by: Richard Cochran <rcochran@...utronix.de>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>  drivers/watchdog/octeon-wdt-main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/watchdog/octeon-wdt-main.c b/drivers/watchdog/octeon-wdt-main.c
> index 14521c8..b55981f 100644
> --- a/drivers/watchdog/octeon-wdt-main.c
> +++ b/drivers/watchdog/octeon-wdt-main.c
> @@ -431,7 +431,7 @@ static int octeon_wdt_cpu_callback(struct notifier_block *nfb,
>  {
>  	unsigned int cpu = (unsigned long)hcpu;
>  
> -	switch (action) {
> +	switch (action & ~CPU_TASKS_FROZEN) {
>  	case CPU_DOWN_PREPARE:
>  		octeon_wdt_disable_interrupt(cpu);
>  		break;