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

["Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx>]

Umm... After checking, the panic due to my mistake to add the debug instruction 
to print the value of processor_pminfo[cpu]->perf. Please just ignore this 
patch.
Thanks for pointing out this.

best regards
yang

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Thursday, September 08, 2011 5:13 PM
> To: Zhang, Yang Z
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx; Keir Fraser
> Subject: Re: [Xen-devel] [PATCH]Make sure processor_pminfo initialized before
> use it
> 
> >>> 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))
> >
> >
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> 
> 


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