Re: [RFC PATCH 2/2] tools/cpupools: Give a name to unnamed cpupools

[Luca Fancellu <luca.fancellu@xxxxxxx>]

> On 17 Nov 2021, at 11:10, Juergen Gross <jgross@xxxxxxxx> wrote:
> 
> On 17.11.21 10:57, Luca Fancellu wrote:
>> With the introduction of boot time cpupools, Xen can
>> create at boot time many cpupools different from the
>> cpupool with id 0.
>> Since these newly created cpupools can't have an
>> entry in Xenstore, name them with the same convention
>> used for the cpupool 0: Pool-<cpupool id>.
>> Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
>> ---
>>  tools/libs/light/libxl_utils.c | 13 ++++++++-----
>>  1 file changed, 8 insertions(+), 5 deletions(-)
>> diff --git a/tools/libs/light/libxl_utils.c b/tools/libs/light/libxl_utils.c
>> index 4699c4a0a3..d97d91ca98 100644
>> --- a/tools/libs/light/libxl_utils.c
>> +++ b/tools/libs/light/libxl_utils.c
>> @@ -147,13 +147,16 @@ int libxl_cpupool_qualifier_to_cpupoolid(libxl_ctx 
>> *ctx, const char *p,
>>  char *libxl_cpupoolid_to_name(libxl_ctx *ctx, uint32_t poolid)
>>  {
>>      unsigned int len;
>> -    char path[strlen("/local/pool") + 12];
>> +    char buffer[strlen("/local/pool") + 12];
>>      char *s;
>>  -    snprintf(path, sizeof(path), "/local/pool/%d/name", poolid);
>> -    s = xs_read(ctx->xsh, XBT_NULL, path, &len);
>> -    if (!s && (poolid == 0))
>> -        return strdup("Pool-0");
>> +    snprintf(buffer, sizeof(buffer), "/local/pool/%d/name", poolid);
>> +    s = xs_read(ctx->xsh, XBT_NULL, buffer, &len);
>> +    if (!s)
>> +    {
>> +        snprintf(buffer, sizeof(buffer), "Pool-%d", poolid);
>> +        return strdup(buffer);
>> +    }
>>      return s;
>>  }
>>  
> 
> This breaks libxl_cpupoolid_is_valid(), as it will now return always
> true, regardless whether the poolid is existing or not.

Hi Juergen,

Yes right, do you think I can use safely xc_cpupool_getinfo(…) when there is no 
entry
in xenstore?
I would check that the returned cpupool id is the same and if it isn’t or if I 
get a null
result, then I will return NULL to ensure libxl_cpupoolid_is_valid(…) works 
again.

Cheers,
Luca

> 
> 
> Juergen
> <OpenPGP_0xB0DE9DD628BF132F.asc>