[dpdk-dev] [PATCH] ethdev: add function name to log message

Ferruh Yigit ferruh.yigit at intel.com
Tue Oct 16 17:55:43 CEST 2018


On 10/12/2018 3:54 PM, Stephen Hemminger wrote:
> On Fri, 12 Oct 2018 14:43:57 +0200
> Adrien Mazarguil <adrien.mazarguil at 6wind.com> wrote:
> 
>> On Fri, Oct 12, 2018 at 11:45:01AM +0100, Ferruh Yigit wrote:
>>> On 10/12/2018 11:42 AM, Ferruh Yigit wrote:  
>>>> On 10/11/2018 6:59 PM, Stephen Hemminger wrote:  
>>>>> @@ -161,8 +161,9 @@ extern "C" {
>>>>>  
>>>>>  extern int rte_eth_dev_logtype;
>>>>>  
>>>>> -#define RTE_ETHDEV_LOG(level, ...) \
>>>>> -	rte_log(RTE_LOG_ ## level, rte_eth_dev_logtype, "" __VA_ARGS__)
>>>>> +#define RTE_ETHDEV_LOG(level, fmt, ...)		\
>>>>> +	rte_log(RTE_LOG_ ## level, rte_eth_dev_logtype, \
>>>>> +		"%s():" fmt, __func__, ## __VA_ARGS__)  
>>>>
>>>> +1 to adding function name, but
>>>>
>>>> failsafe is giving build error [1] with clang because of ## usage [2], that is
>>>> why I add this as ` "" __VA_ARGS__` at first place but you can't do this trick
>>>> if __VA_ARGS__ used after fmt.
>>>>
>>>> I am not aware of a solution for this, __VA_OPT__(,) also didn't worked with clang.  
>>>
>>> +cc Adrien & Gaetan,
>>>
>>> I saw Adrien put some "workaround" to this for mlx5  
>>
>> Yes, through RTE_FMT() (rte_common.h). Something like this:
>>
>>  #define RTE_ETHDEV_LOG(level, fmt, ...) \
>>      rte_log(RTE_LOG_ ## level, \
>>              rte_eth_dev_logtype, \
>>              "%s():" fmt, \
>>              __func__, \
>>              ## __VA_ARGS__)
>>
>> Can be rewritten like that:
>>
>>  #define RTE_ETHDEV_LOG(level, ...) \
>>      rte_log(RTE_LOG_ ## level, \
>>              rte_eth_dev_logtype, \
>>              RTE_FMT("%s():" RTE_FMT_HEAD(__VA_ARGS__,), \
>>                      __func__, \
>>                      RTE_FMT_TAIL(__VA_ARGS__,)))
>>
>> Although not too pretty and convenient, it does the job. In short:
>>
>> - Remove "fmt" argument from prototype.
>> - Enclose format string and its arguments in RTE_FMT().
>> - Replace "fmt" with RTE_FMT_HEAD(__VA_ARGS__,).
>> - Replace "## __VA_ARGS__" with RTE_FMT_TAIL(__VA_ARGS__,).
>> - Yes, trailing commas are mandatory in RTE_FMT_(HEAD|TAIL)().
>> - Note it quietly appends a dummy "%.0s" argument to the format string.
>>
>>>> [1]
>>>> .../build/include/rte_ethdev.h:166:26: error: token pasting of ',' and
>>>> __VA_ARGS__ is a GNU extension [-Werror,-Wgnu-zero-variadic-macro-arguments]
>>>>                 "%s():" fmt, __func__, ## __VA_ARGS__)
>>>>                                        ^
>>>>
>>>> [2]
>>>> This seems because of "-pedantic" argument driver uses, and other PMDs using
>>>> "-pedantic", like mlx,  will have same error although they are disable by
>>>> default and error not observed in default build.
>>>>   
>>>   
>>
> 
> Since zero varadic macros is a GNU extension, maybe just adding GNU source?

I think `-pedantic` is preventing using extension whether we have `_GNU_SOURCE`
or not.

Gaetan,

Why we have `-pedantic` option enabled for failsafe?


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