> On Dec 14, 2018, at 2:40 PM, Jeff Shaw <jeffrey.b.s...@intel.com> wrote:
>
> Compilers that do not support the C99 standard, or do not implement
> gcc extensions, may not support variable length arrays.
>
> The code prior to this commit produced the following warning when
> compiled with "-Wvla -std=c90".
>
> warning: ISO C90 forbids variable length array ‘array’ [-Wvla]
>
> This commit removes the variable length array from the PMD debug
> trace function by allocating memory dynamically on the stack using
> alloca().
>
> Signed-off-by: Jeff Shaw <jeffrey.b.s...@intel.com>
> ---
>
> V2:
> - Reference C99 in commit message instead of C11.
> - Remove unnecessary cast of alloca() returning void *.
>
> ---
> lib/librte_eal/common/include/rte_dev.h | 19 +++++++++----------
> 1 file changed, 9 insertions(+), 10 deletions(-)
>
> diff --git a/lib/librte_eal/common/include/rte_dev.h
> b/lib/librte_eal/common/include/rte_dev.h
> index a9724dc91..6d7a220b0 100644
> --- a/lib/librte_eal/common/include/rte_dev.h
> +++ b/lib/librte_eal/common/include/rte_dev.h
> @@ -47,22 +47,21 @@ __attribute__((format(printf, 2, 0)))
> static inline void
> rte_pmd_debug_trace(const char *func_name, const char *fmt, ...)
> {
> + char *buffer;
> + int buf_len;
> va_list ap;
>
> va_start(ap, fmt);
> + buf_len = vsnprintf(NULL, 0, fmt, ap) + 1;
> + va_end(ap);
>
> - {
> - char buffer[vsnprintf(NULL, 0, fmt, ap) + 1];
> + buffer = alloca(buf_len);
Looks like some formatting problems with tab and/or spaces. DPDK is tabs of
size 8 and no spaces before tabs.
The code looks fine to me, except for the calling vsnprintf twice. Could we
have used char buffer[SOME_NUMBER_THAT_IS_REASONABLE];
This would remove the two calls to vsnprintf() and alloca usage.
If everyone is OK with it then I am ok after the formatting problems get fixed.
>
> - va_end(ap);
> -
> - va_start(ap, fmt);
> - vsnprintf(buffer, sizeof(buffer), fmt, ap);
> - va_end(ap);
> + va_start(ap, fmt);
> + vsnprintf(buffer, buf_len, fmt, ap);
> + va_end(ap);
>
> - rte_log(RTE_LOG_ERR, RTE_LOGTYPE_PMD, "%s: %s",
> - func_name, buffer);
> - }
> + rte_log(RTE_LOG_ERR, RTE_LOGTYPE_PMD, "%s: %s", func_name, buffer);
> }
>
> /*
> --
> 2.14.3
>
Regards,
Keith
