On Fri, Dec 14, 2018 at 10:36:03AM -0800, Stephen Hemminger wrote:
> On Fri, 14 Dec 2018 08:38:27 -0800
> Jeff Shaw <jeffrey.b.s...@intel.com> wrote:
>
> > Compilers that do not support the C11 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>
> > ---
> > 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..af772872b 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 = (char *)alloca(buf_len);
>
> alloca is void * so cast is not necessary.
I get a compiler warning on Windows, hence the cast. I suppose we could
disable the warning.
>
> You might be able to skip the buffering step entirely by using rte_log
> a little more creatively, see how other logging works.
Probably right... this eventuall needs to be done in ~100 other places,
most of which aren't used with rte_log(), so it seemed fitting.
>
> But to go further since rte_pmd_debug_trace is not used anywhere in
> current code base in DPDK, it should just be removed.
Much better solution :)
