RE: [Xen-devel] Re: xenpm fail

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

Nothing print with your patch.

best regards
yang


> -----Original Message-----
> From: Ian Campbell [mailto:Ian.Campbell@xxxxxxxxxx]
> Sent: Friday, October 29, 2010 5:42 PM
> To: Zhang, Yang Z
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx; Ian Jackson
> Subject: Re: [Xen-devel] Re: xenpm fail
> 
> On Fri, 2010-10-29 at 10:26 +0100, Ian Campbell wrote:
> > On Fri, 2010-10-29 at 09:32 +0100, Zhang, Yang Z wrote:
> > > Hi ian
> > > I find Cs 22292 cause xenpm broken. When run "xenpm start" or "xenpm
> > > get-cpuidle-states" and other xenmpm command, it will get segment
> > > fault.
> > > After do some investigation, I find call xc_pm_get_cxstat() will free
> > > the cxstat->tiggers,
> > > For example:
> > > Here is some code form my test.c.
> > >
> > > struct xc_cx_stat cxstatinfo, *cxstat = &cxstatinfo;
> > >
> > > cxstat->triggers = malloc(max_cx_num * sizeof(uint64_t));
> > >
> > > if ( !cxstat->triggers ) {
> > >   printf("get memory fail");
> > >   return NOMEM;
> > > }
> > > ret = xc_pm_get_cxstat(xc_handle, cpu, cxstat);
> >
> > what is ret at this point?
> >
> > > printf("triggers=%lx \n", cxstat->triggers[0]);
> > >
> > > Run it, and it will show segment fault at print the cxtat->tiggers[0].
> > > It seems that xc_pm_get_cxstat() will free cxstat->triggers which we
> > > allocate memory before, and then when try to touch cxstat->tiggers[0],
> > > the issue raised.
> >
> > I can't see any code which frees cxstat->triggers in xc_pm_get_cxstat,
> > there is only code which frees the bounce buffer.
> >
> > Perhaps the issue you are seeing is with get_cxstat_by_cpuid from
> > xenpm.c rather than xc_pm_get_cxstat directly? I notice that
> > get_cxstat_by_cpuid is called on one occasion without checking the
> > return code and that it frees the trigger array when xc_pm_get_cxstat
> > fails so a new failure introduced by 22292 could cause this?
> >
> > What hardware is this on? What is max_cx_num and max_cpu_nr for you?
> 
> Please could you also try this debug patch
> 
> diff -r a1b39d2b9001 tools/misc/xenpm.c
> --- a/tools/misc/xenpm.c      Fri Oct 22 15:14:51 2010 +0100
> +++ b/tools/misc/xenpm.c      Fri Oct 29 10:41:37 2010 +0100
> @@ -121,6 +121,7 @@ static int get_cxstat_by_cpuid(xc_interf
>      cxstat->residencies = malloc(max_cx_num * sizeof(uint64_t));
>      if ( !cxstat->residencies )
>      {
> +        fprintf(stderr, "failed to allocate residencies, freeing 
> triggers\n");
>          free(cxstat->triggers);
>          return -ENOMEM;
>      }
> @@ -129,6 +130,7 @@ static int get_cxstat_by_cpuid(xc_interf
>      if( ret )
>      {
>          int temp = errno;
> +        fprintf(stderr, "xc_pm_get_cx_stat failed %d %d, freeing buffers\n",
> ret, errno);
>          free(cxstat->triggers);
>          free(cxstat->residencies);
>          cxstat->triggers = NULL;
> 

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