Re: [PATCH] intel_idle: Check cpu_idle_get_driver() for NULL before dereferencing it.

From: Rafael J. Wysocki
Date: Sat Aug 04 2012 - 17:50:51 EST


On Thursday, August 02, 2012, Konrad Rzeszutek Wilk wrote:
> If the machine is booted without any cpu_idle driver set
> (b/c disable_cpuidle() has been called) we should follow
> other users of cpu_idle API and check the return value
> for NULL before using it.
>
> Reported-by: Mark van Dijk <mark@xxxxxxxxxxxxxx>
> Tested-by: Mark van Dijk <mark@xxxxxxxxxxxxxx>
> Suggested-by: Jan Beulich <JBeulich@xxxxxxxx>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
> drivers/idle/intel_idle.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
> index f559088..7383aa0 100644
> --- a/drivers/idle/intel_idle.c
> +++ b/drivers/idle/intel_idle.c
> @@ -607,7 +607,7 @@ static int __init intel_idle_init(void)
> retval = cpuidle_register_driver(&intel_idle_driver);
> if (retval) {

What about:

struct cpuidle_driver *drv = cpuidle_get_driver();

printk(KERN_DEBUG PREFIX "intel_idle yielding to %s",
drv ? drv->name : "none");

> printk(KERN_DEBUG PREFIX "intel_idle yielding to %s",
> - cpuidle_get_driver()->name);
> + cpuidle_get_driver() ? cpuidle_get_driver()->name : "none");
> return retval;
> }
>
>

Rafael
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