Re: [Xen-devel] [PATCH]Make sure processor_pminfo initialized before use it

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 08.09.11 at 08:09, "Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx> wrote:
> Make sure processor_pminfo not null before use it
> 
> If processor_pminfo not initialized, it will cause xen panic.

Mind pointing out what panic you observed, because ...

> Signed-off-by: Yang Zhang <yang.z.zhang@xxxxxxxxx>
> 
> diff -r bdd19847ae63 xen/drivers/cpufreq/cpufreq.c
> --- a/xen/drivers/cpufreq/cpufreq.c     Wed Sep 07 10:37:48 2011 +0100
> +++ b/xen/drivers/cpufreq/cpufreq.c     Thu Sep 08 13:40:23 2011 +0800
> @@ -91,7 +91,7 @@ int __init cpufreq_register_governor(str
> 
>  int cpufreq_limit_change(unsigned int cpu)
>  {
> -    struct processor_performance *perf = &processor_pminfo[cpu]->perf;
> +    struct processor_performance *perf;

... this (and all other changed instances below) is not actually
de-referencing processor_pminfo[cpu], and the first de-reference
always is only after that one got checked against NULL.

Jan

>      struct cpufreq_policy *data;
>      struct cpufreq_policy policy;
> 
> @@ -99,6 +99,7 @@ int cpufreq_limit_change(unsigned int cp
>          !processor_pminfo[cpu])
>          return -ENODEV;
> 
> +    perf = &processor_pminfo[cpu]->perf;
>      if (perf->platform_limit >= perf->state_count)
>          return -EINVAL;
> 
> @@ -120,12 +121,14 @@ int cpufreq_add_cpu(unsigned int cpu)
>      struct cpufreq_dom *cpufreq_dom = NULL;
>      struct cpufreq_policy new_policy;
>      struct cpufreq_policy *policy;
> -    struct processor_performance *perf = &processor_pminfo[cpu]->perf;
> +    struct processor_performance *perf;
> 
>      /* to protect the case when Px was not controlled by xen */
> -    if (!processor_pminfo[cpu]      ||
> -        !(perf->init & XEN_PX_INIT) ||
> -        !cpu_online(cpu))
> +    if (!processor_pminfo[cpu] || !cpu_online(cpu))
> +        return -EINVAL;
> +
> +    perf = &processor_pminfo[cpu]->perf;
> +    if (!(perf->init & XEN_PX_INIT))
>          return -EINVAL;
> 
>      if (!cpufreq_driver)
> @@ -261,12 +264,14 @@ int cpufreq_del_cpu(unsigned int cpu)
>      struct list_head *pos;
>      struct cpufreq_dom *cpufreq_dom = NULL;
>      struct cpufreq_policy *policy;
> -    struct processor_performance *perf = &processor_pminfo[cpu]->perf;
> +    struct processor_performance *perf;
> 
>      /* to protect the case when Px was not controlled by xen */
> -    if (!processor_pminfo[cpu]      ||
> -        !(perf->init & XEN_PX_INIT) ||
> -        !cpu_online(cpu))
> +    if (!processor_pminfo[cpu] || !cpu_online(cpu))
> +        return -EINVAL;
> +
> +    perf = &processor_pminfo[cpu]->perf;
> +    if (!(perf->init & XEN_PX_INIT))
>          return -EINVAL;
> 
>      if (!per_cpu(cpufreq_cpu_policy, cpu))
> 
> 
> 
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> http://lists.xensource.com/xen-devel 




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