[dpdk-dev] [RFC PATCH 1/6] eal: define container macro

[Shreyansh Jain]

On Thursday 17 November 2016 05:36 PM, Jan Blunck wrote:
> On Thu, Nov 17, 2016 at 6:30 AM, Shreyansh Jain <shreyansh.jain at nxp.com> wrote:
>> From: Jan Viktorin <viktorin at rehivetech.com>
>>
>> Signed-off-by: Jan Viktorin <viktorin at rehivetech.com>
>> Signed-off-by: Shreyansh Jain <shreyansh.jain at nxp.com>
>> ---
>>  lib/librte_eal/common/include/rte_common.h | 18 ++++++++++++++++++
>>  1 file changed, 18 insertions(+)
>>
>> diff --git a/lib/librte_eal/common/include/rte_common.h b/lib/librte_eal/common/include/rte_common.h
>> index db5ac91..8152bd9 100644
>> --- a/lib/librte_eal/common/include/rte_common.h
>> +++ b/lib/librte_eal/common/include/rte_common.h
>> @@ -331,6 +331,24 @@ rte_bsf32(uint32_t v)
>>  #define offsetof(TYPE, MEMBER)  __builtin_offsetof (TYPE, MEMBER)
>>  #endif
>>
>> +/**
>> + * Return pointer to the wrapping struct instance.
>> + * Example:
>> + *
>> + *  struct wrapper {
>> + *      ...
>> + *      struct child c;
>> + *      ...
>> + *  };
>> + *
>> + *  struct child *x = obtain(...);
>> + *  struct wrapper *w = container_of(x, struct wrapper, c);
>> + */
>> +#ifndef container_of
>> +#define container_of(p, type, member) \
>> +       ((type *) (((char *) (p)) - offsetof(type, member)))
>
> Are there any reasons why you choose to implement this in a non-type
> safe way? Catching obvious bugs at compile time is in the interest of
> us and our users from my point of view.

No specific reason. I just took an existing patchset floating in ML. If 
you can point me to some better implementation, I will use that.

>
>
>> +#endif
>> +
>>  #define _RTE_STR(x) #x
>>  /** Take a macro value and get a string version of it */
>>  #define RTE_STR(x) _RTE_STR(x)
>> --
>> 2.7.4
>>
>


-- 
-
Shreyansh