[Xen-devel] Re: libxc: fix bug of xc_tbuf_get_size()

[Yu Zhiguo <yuzg@xxxxxxxxxxxxxx>]

Hi keir and George,

Keir Fraser wrote:
> When did this change, and who changed it? It would be good to collect an
> appropriate Ack, e.g., from George Dunlap, if it was his xentrace changes.
> 

 I found this bug when I try 'xentrace_setsize'. The default
'current tbuf size' should be 0x14 but 0x2 outputted.
 xc_tbuf_set_size() sets the tbuf size, it's ok. But xc_tbuf_get_size()
tries to get the size of t_info pages.

 Could George have a look at this problem?

Regards,

Yu

> I can't take un-acked patches from non-maintainers on stuff I don't have
> good knowledge of myself, this late in the release cycle.
> 
>  -- Keir
> 
> On 09/02/2010 10:57, "Yu Zhiguo" <yuzg@xxxxxxxxxxxxxx> wrote:
> 
>> The size in pages of trace buffer should be t_info->tbuf_size
>> rather than t_info pages.
>>
>> Signed-off-by: Yu Zhiguo <yuzg@xxxxxxxxxxxxxx>
>>
>> diff --git a/tools/libxc/xc_tbuf.c b/tools/libxc/xc_tbuf.c
>> --- a/tools/libxc/xc_tbuf.c
>> +++ b/tools/libxc/xc_tbuf.c
>> @@ -15,6 +15,7 @@
>>   */
>>  
>>  #include "xc_private.h"
>> +#include <xen/trace.h>
>>  
>>  static int tbuf_enable(int xc_handle, int enable)
>>  {
>> @@ -44,6 +45,7 @@
>>  
>>  int xc_tbuf_get_size(int xc_handle, unsigned long *size)
>>  {
>> +    struct t_info *t_info;
>>      int rc;
>>      DECLARE_SYSCTL;
>>  
>> @@ -52,9 +54,19 @@
>>      sysctl.u.tbuf_op.cmd  = XEN_SYSCTL_TBUFOP_get_info;
>>  
>>      rc = xc_sysctl(xc_handle, &sysctl);
>> -    if (rc == 0)
>> -        *size = sysctl.u.tbuf_op.size;
>> -    return rc;
>> +    if ( rc != 0 )
>> +        return rc;
>> +
>> +    t_info = xc_map_foreign_range(xc_handle, DOMID_XEN,
>> +                    sysctl.u.tbuf_op.size, PROT_READ | PROT_WRITE,
>> +                    sysctl.u.tbuf_op.buffer_mfn);
>> +
>> +    if ( t_info == NULL || t_info->tbuf_size == 0 )
>> +        return -1;
>> +
>> +    *size = t_info->tbuf_size;
>> +
>> +    return 0;
>>  }
>>  
>>  int xc_tbuf_enable(int xc_handle, unsigned long pages, unsigned long *mfn,
>>
> 
> 
> 
> 
> 


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