Re: [dpdk-dev] [PATCH v1] net/mlx4: fix missing initializers for old GCC

[Adrien Mazarguil <adrien.mazarguil@6wind.com>]

Hi Nelio,

On Tue, Oct 24, 2017 at 04:03:15PM +0200, Nélio Laranjeiro wrote:
> Hi Moti,
> 
> On Tue, Oct 24, 2017 at 03:35:33PM +0300, Moti Haimovsky wrote:
> > This patch works around compilation issues seen on RHEL 7.2
> > using GCC 4.8.5:
> > 
> >    [...] In function 'mlx4_rss_init':
> >    [...]/mlx4_rxq.c:433:19: error: 'wq_num' may be used uninitialized
> >         in this function [-Werror=maybe-uninitialized]
> > 
> > Fixes: ff3397e90080 ("net/mlx4: relax Rx queue configuration order")
> > 
> > Signed-off-by: Moti Haimovsky <motih@mellanox.com>
> > ---
> >  drivers/net/mlx4/mlx4_rxq.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/net/mlx4/mlx4_rxq.c b/drivers/net/mlx4/mlx4_rxq.c
> > index fb28290..4c50077 100644
> > --- a/drivers/net/mlx4/mlx4_rxq.c
> > +++ b/drivers/net/mlx4/mlx4_rxq.c
> > @@ -417,6 +417,8 @@ void mlx4_rss_detach(struct mlx4_rss *rss)
> >  		if (wq) {
> >  			wq_num = wq->wq_num;
> >  			claim_zero(ibv_destroy_wq(wq));
> > +		} else {
> > +			 wq_num = 0; /* Shut up GCC 4.8 warnings. */
> >  		}
> >  		claim_zero(ibv_destroy_cq(cq));
> >  		if (!wq) {
> 
> Why not initialising the wq_num at 0 directly instead of adding this
> else branch?

Actually that was my suggestion, it is done to highlight the code path
where buggy GCC versions choke on what they mistake for an uninitialized
variable. Initializing this variable earlier could possibly hide bugs
otherwise.

Patch is OK for me as is:

Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>

-- 
Adrien Mazarguil
6WIND