Re: [dpdk-dev] [PATCH v3] eal: simplify RTE_PMD_DEBUG_TRACE

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 12/21/2018 6:18 PM, Jeff Shaw wrote:
> From: Stephen Hemminger <stephen@networkplumber.org>
> 
> Use rte_log directly, eliminating no longer used rte_pmd_dev_trace
> function. This removes variable length array which is problem on
> Windows and other compilers not doing C99.
> 
> Also, drop unused RTE_PROC_PRIMARY macros.
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> Signed-off-by: Jeff Shaw <jeffrey.b.shaw@intel.com>
> ---
> 
> V3:
>   - Fix checkpatch error:
>       ERROR:SPACING: space required before the open parenthesis '('
> 
> V2:
>   - Changed named variable "args..." to use "..." with ##__VA_LIST__.
>     Pasting is necessary to support case where only the format string,
>     with no arguments, is passed.
> 
> ---
>  lib/librte_eal/common/include/rte_dev.h | 44 +++------------------------------
>  1 file changed, 4 insertions(+), 40 deletions(-)
> 
> diff --git a/lib/librte_eal/common/include/rte_dev.h b/lib/librte_eal/common/include/rte_dev.h
> index a9724dc91..d7b3c1576 100644
> --- a/lib/librte_eal/common/include/rte_dev.h
> +++ b/lib/librte_eal/common/include/rte_dev.h
> @@ -43,54 +43,18 @@ typedef void (*rte_dev_event_cb_fn)(const char *device_name,
>  					enum rte_dev_event_type event,
>  					void *cb_arg);
>  
> -__attribute__((format(printf, 2, 0)))
> -static inline void
> -rte_pmd_debug_trace(const char *func_name, const char *fmt, ...)
> -{
> -	va_list ap;
> -
> -	va_start(ap, fmt);
> -
> -	{
> -		char buffer[vsnprintf(NULL, 0, fmt, ap) + 1];
> -
> -		va_end(ap);
> -
> -		va_start(ap, fmt);
> -		vsnprintf(buffer, sizeof(buffer), fmt, ap);
> -		va_end(ap);
> -
> -		rte_log(RTE_LOG_ERR, RTE_LOGTYPE_PMD, "%s: %s",
> -			func_name, buffer);
> -	}
> -}
> -
>  /*
>   * Enable RTE_PMD_DEBUG_TRACE() when at least one component relying on the
>   * RTE_*_RET() macros defined below is compiled in debug mode.
>   */
>  #if defined(RTE_LIBRTE_EVENTDEV_DEBUG)
> -#define RTE_PMD_DEBUG_TRACE(...) \
> -	rte_pmd_debug_trace(__func__, __VA_ARGS__)
> +#define RTE_PMD_DEBUG_TRACE(fmt, ...)					\
> +	rte_log(RTE_LOG_ERR, RTE_LOGTYPE_PMD, "%s: " fmt, __func__,	\
> +		##__VA_ARGS__)

When RTE_PMD_DEBUG_TRACE enabled, mlx4/5 drivers are causing build error because
of '-pedantic' argument [1].
error is in 'RTE_FUNC_PTR_OR_ERR_RET' & 'RTE_FUNC_PTR_OR_RET', what do you think
removing 'RTE_PMD_DEBUG_TRACE' completely from these macros? Since
'RTE_PMD_DEBUG_TRACE' already enabled only with 'RTE_LIBRTE_EVENTDEV_DEBUG' it
is already disabled mostly.
Another option can be replacing 'RTE_PMD_DEBUG_TRACE' with 'rte_log', but with
DEBUG log type to not introduce new logs [2].

[1]
error: token pasting of ',' and __VA_ARGS__ is a GNU extension
[-Werror,-Wgnu-zero-variadic-macro-arguments]

[2]
  -   RTE_PMD_DEBUG_TRACE("Function not supported\n"); \
  +   rte_log(RTE_LOG_ERR, RTE_LOGTYPE_PMD, "%s: Function not supported\n",
__func__); \