linux-kernel - Re: [RFC PATCH 8/8] watchdog: Fix internal state with boot user disabled watchdog

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Message-ID: <20130520175454.GK133453@redhat.com>
Date:	Mon, 20 May 2013 13:54:54 -0400
From:	Don Zickus <dzickus@...hat.com>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [RFC PATCH 8/8] watchdog: Fix internal state with boot user
 disabled watchdog

On Mon, May 20, 2013 at 06:01:56PM +0200, Frederic Weisbecker wrote:
> When the watchdog is disabled through the 'nmi_watchdog=0'
> boot parameter, the watchdog_running internal state isn't
> cleared. Hence further enablements through sysctl/procfs
> are ignored because the subsystem spuriously thinks it's
> already running.
> 
> Initialize it properly on boot.

Looks fine to me.  Can't think of a case where this breaks something.

Acked-by: Don Zickus <dzickus@...hat.com>

> 
> Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
> Cc: Don Zickus <dzickus@...hat.com>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Peter Zijlstra <peterz@...radead.org>
> ---
>  kernel/watchdog.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/watchdog.c b/kernel/watchdog.c
> index 10776fe..3fa5df20 100644
> --- a/kernel/watchdog.c
> +++ b/kernel/watchdog.c
> @@ -31,7 +31,7 @@
>  
>  int watchdog_user_enabled = 1;
>  int __read_mostly watchdog_thresh = 10;
> -static int __read_mostly watchdog_running = 1;
> +static int __read_mostly watchdog_running;
>  static u64 __read_mostly sample_period;
>  
>  static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
> @@ -545,10 +545,10 @@ void __init lockup_detector_init(void)
>  {
>  #ifdef CONFIG_NO_HZ_FULL
>  	watchdog_user_enabled = 0;
> -	watchdog_running = 0;
>  	pr_warning("Disabled lockup detectors by default because of full dynticks\n");
>  	pr_warning("You can overwrite that with 'sysctl -w kernel.watchdog=1'\n");
>  #endif
> +	watchdog_running = watchdog_user_enabled;
>  	set_sample_period();
>  	if (smpboot_register_percpu_thread(&watchdog_threads)) {
>  		pr_err("Failed to create watchdog threads, disabled\n");
> -- 
> 1.7.5.4
> 
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