[dpdk-dev] [PATCH v7 22/25] mlx5: work around spurious compilation errors

[Adrien Mazarguil]

On Mon, Jun 27, 2016 at 01:12:15PM +0100, Bruce Richardson wrote:
> On Fri, Jun 24, 2016 at 03:18:01PM +0200, Nelio Laranjeiro wrote:
> > From: Adrien Mazarguil 
> > 
> > Since commit "mlx5: resurrect Tx gather support", older GCC versions (such
> > as 4.8.5) may complain about the following:
> > 
> >  mlx5_rxtx.c: In function `mlx5_tx_burst':
> >  mlx5_rxtx.c:705:25: error: `wqe' may be used uninitialized in this
> >  function [-Werror=maybe-uninitialized]
> > 
> >  mlx5_rxtx.c: In function `mlx5_tx_burst_inline':
> >  mlx5_rxtx.c:864:25: error: `wqe' may be used uninitialized in this
> >  function [-Werror=maybe-uninitialized]
> > 
> > In both cases, this code cannot be reached when wqe is not initialized.
> > 
> > Considering older GCC versions are still widely used, work around this
> > issue by initializing wqe preemptively, even if it should not be necessary.
> > 
> > Signed-off-by: Adrien Mazarguil 
> 
> Since the previous patch is known to break the build on older compilers, I 
> think
> it would be better to merge this patch into the previous to prevent the break
> from occurring in the first place. That will help with any future git-bisects
> that people run.

Makes sense, in fact I only kept it separate to decribe why setting these
variables was necessary, in case someone wondered.

> If there is no objection, and no other issues appear requiring a new rev of
> this patchset, I'll merge patches 21 and 22 on apply.

That's fine by me.

-- 
Adrien Mazarguil
6WIND

[dpdk-dev] [PATCH v7 22/25] mlx5: work around spurious compilation errors

[Bruce Richardson]

On Fri, Jun 24, 2016 at 03:18:01PM +0200, Nelio Laranjeiro wrote:
> From: Adrien Mazarguil 
> 
> Since commit "mlx5: resurrect Tx gather support", older GCC versions (such
> as 4.8.5) may complain about the following:
> 
>  mlx5_rxtx.c: In function `mlx5_tx_burst':
>  mlx5_rxtx.c:705:25: error: `wqe' may be used uninitialized in this
>  function [-Werror=maybe-uninitialized]
> 
>  mlx5_rxtx.c: In function `mlx5_tx_burst_inline':
>  mlx5_rxtx.c:864:25: error: `wqe' may be used uninitialized in this
>  function [-Werror=maybe-uninitialized]
> 
> In both cases, this code cannot be reached when wqe is not initialized.
> 
> Considering older GCC versions are still widely used, work around this
> issue by initializing wqe preemptively, even if it should not be necessary.
> 
> Signed-off-by: Adrien Mazarguil 

Since the previous patch is known to break the build on older compilers, I think
it would be better to merge this patch into the previous to prevent the break
from occurring in the first place. That will help with any future git-bisects
that people run.

If there is no objection, and no other issues appear requiring a new rev of
this patchset, I'll merge patches 21 and 22 on apply.

Regards,
/Bruce

[dpdk-dev] [PATCH v7 22/25] mlx5: work around spurious compilation errors

[Nelio Laranjeiro]

From: Adrien Mazarguil 

Since commit "mlx5: resurrect Tx gather support", older GCC versions (such
as 4.8.5) may complain about the following:

 mlx5_rxtx.c: In function `mlx5_tx_burst':
 mlx5_rxtx.c:705:25: error: `wqe' may be used uninitialized in this
 function [-Werror=maybe-uninitialized]

 mlx5_rxtx.c: In function `mlx5_tx_burst_inline':
 mlx5_rxtx.c:864:25: error: `wqe' may be used uninitialized in this
 function [-Werror=maybe-uninitialized]

In both cases, this code cannot be reached when wqe is not initialized.

Considering older GCC versions are still widely used, work around this
issue by initializing wqe preemptively, even if it should not be necessary.

Signed-off-by: Adrien Mazarguil 
---
 drivers/net/mlx5/mlx5_rxtx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
index c72e7ce..8b67949 100644
--- a/drivers/net/mlx5/mlx5_rxtx.c
+++ b/drivers/net/mlx5/mlx5_rxtx.c
@@ -593,7 +593,7 @@ mlx5_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, 
uint16_t pkts_n)
unsigned int j = 0;
unsigned int max;
unsigned int comp;
-   volatile union mlx5_wqe *wqe;
+   volatile union mlx5_wqe *wqe = NULL;

if (unlikely(!pkts_n))
return 0;
@@ -741,7 +741,7 @@ mlx5_tx_burst_inline(void *dpdk_txq, struct rte_mbuf 
**pkts, uint16_t pkts_n)
unsigned int j = 0;
unsigned int max;
unsigned int comp;
-   volatile union mlx5_wqe *wqe;
+   volatile union mlx5_wqe *wqe = NULL;
unsigned int max_inline = txq->max_inline;

if (unlikely(!pkts_n))
-- 
2.1.4