[dpdk-dev] [PATCH v3 2/4] ethdev: move error checking macros to header

Bruce Richardson bruce.richardson at intel.com
Fri Nov 6 18:10:07 CET 2015


On Thu, Nov 05, 2015 at 04:09:18PM +0100, Adrien Mazarguil wrote:
> 
> I won't argue against this as it's obviously more complex than the original
> method, however note that users of the RTE_PMD_DEBUG_TRACE() macro do not
> have to modify their code. They shouldn't care about the implementation.
> 
> Also note that we can do much cleaner code if we drop the all macros
> implementation using a (much easier to debug) static inline function,
> only perhaps with a wrapper macro that provides __LINE__, __func__ and
> __FILE__ as arguments. Nontrival code shouldn't be done in macros anyway.
> 
Getting something working with __FILE__ and probably __LINE__ would be easy enough
with a helper macro, but __func__ is not so easy as it's not a preprocessor symbol
[since the pre-processor has no idea what function you are in].

However, using func, here is the best I've come up with so far. It's not that
pretty, but it's probably easier to work with than the macro version.

 #ifdef RTE_LIBRTE_ETHDEV_DEBUG
 -#define RTE_PMD_DEBUG_TRACE(fmt, args...) \
 -               RTE_LOG(ERR, PMD, "%s: " fmt, __func__, ## args)
 +#define RTE_PMD_DEBUG_TRACE(...) \
 +               rte_pmd_debug_trace(__func__, __VA_ARGS__)
 +
 +static inline void
 +rte_pmd_debug_trace(const char *func_name, const char *fmt, ...)
 +{
 +       static __thread char buffer[128];
 +       char *out_buf = buffer;
 +       unsigned count;
 +       va_list ap;
 +
 +       count = snprintf(buffer, sizeof(buffer), "%s: %s", func_name, fmt);
 +       if (count >= sizeof(buffer)) { // truncated output
 +               char *new_buf = malloc(count + 1);
 +               if (new_buf == NULL) // no memory, just print 128 chars
 +                       goto print_buffer;
 +               snprintf(new_buf, count + 1, "%s: %s", func_name, fmt);
 +               va_start(ap, fmt);
 +               rte_vlog(RTE_LOG_ERR, RTE_LOGTYPE_PMD, buffer, ap);
 +               va_end(ap);
 +               free(new_buf);
 +               return;
 +       }
 +
 +print_buffer:
 +       va_start(ap, fmt);
 +       rte_vlog(RTE_LOG_ERR, RTE_LOGTYPE_PMD, out_buf, ap);
 +       va_end(ap);
 +}
  #else
  #define RTE_PMD_DEBUG_TRACE(fmt, args...)
  #endif

Comments or improvements?

/Bruce


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