Re: BUG: unable to handle kernel NULL pointer dereference at 00000002

[Mike Galbraith <efault@gmx.de>]

On Tue, 2008-07-29 at 00:26 +0200, Frederik Deweerdt wrote:
> Hello  Aneesh,
> 
> On Fri, Jul 25, 2008 at 03:23:17PM +0530, Aneesh Kumar K.V wrote:
> > [  163.378265] BUG: unable to handle kernel NULL pointer dereference at 00000002
> > [  163.378276] IP: [<c0124933>] sched_power_savings_store+0x13/0x70
> 
> Does the attached patch solve the problem?

Patch seems to have missed the boat for rc1 too.

> 
> Regards,
> Frederik
> 
> diff --git a/kernel/sched.c b/kernel/sched.c
> index 0047bd9..090b397 100644
> --- a/kernel/sched.c
> +++ b/kernel/sched.c
> @@ -7643,34 +7643,30 @@ static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt)
>  }
>  
>  #ifdef CONFIG_SCHED_MC
> -static ssize_t sched_mc_power_savings_show(struct sys_device *dev,
> -				struct sysdev_attribute *attr, char *page)
> +static ssize_t sched_mc_power_savings_show(struct sysdev_class *cls, char *page)
>  {
>  	return sprintf(page, "%u\n", sched_mc_power_savings);
>  }
> -static ssize_t sched_mc_power_savings_store(struct sys_device *dev,
> -					    struct sysdev_attribute *attr,
> +static ssize_t sched_mc_power_savings_store(struct sysdev_class *cls,
>  					    const char *buf, size_t count)
>  {
>  	return sched_power_savings_store(buf, count, 0);
>  }
> -static SYSDEV_ATTR(sched_mc_power_savings, 0644, sched_mc_power_savings_show,
> +static SYSDEV_CLASS_ATTR(sched_mc_power_savings, 0644, sched_mc_power_savings_show,
>  		   sched_mc_power_savings_store);
>  #endif
>  
>  #ifdef CONFIG_SCHED_SMT
> -static ssize_t sched_smt_power_savings_show(struct sys_device *dev,
> -				struct sysdev_attribute *attr, char *page)
> +static ssize_t sched_smt_power_savings_show(struct sysdev_class *cls, char *page)
>  {
>  	return sprintf(page, "%u\n", sched_smt_power_savings);
>  }
> -static ssize_t sched_smt_power_savings_store(struct sys_device *dev,
> -					     struct sysdev_attribute *attr,
> +static ssize_t sched_smt_power_savings_store(struct sysdev_class *cls,
>  					     const char *buf, size_t count)
>  {
>  	return sched_power_savings_store(buf, count, 1);
>  }
> -static SYSDEV_ATTR(sched_smt_power_savings, 0644, sched_smt_power_savings_show,
> +static SYSDEV_CLASS_ATTR(sched_smt_power_savings, 0644, sched_smt_power_savings_show,
>  		   sched_smt_power_savings_store);
>  #endif
>  
> @@ -7680,13 +7676,13 @@ int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls)
>  
>  #ifdef CONFIG_SCHED_SMT
>  	if (smt_capable())
> -		err = sysfs_create_file(&cls->kset.kobj,
> -					&attr_sched_smt_power_savings.attr);
> +		err = sysdev_class_create_file(cls,
> +					       &attr_sched_smt_power_savings);
>  #endif
>  #ifdef CONFIG_SCHED_MC
>  	if (!err && mc_capable())
> -		err = sysfs_create_file(&cls->kset.kobj,
> -					&attr_sched_mc_power_savings.attr);
> +		err = sysdev_class_create_file(cls,
> +					       &attr_sched_mc_power_savings);
>  #endif
>  	return err;
>  }