[dpdk-dev] [PATCH 1/2] net/mlx5: fix clang compilation

[Nelio Laranjeiro <nelio.laranjeiro@6wind.com>]

On redhat 7.2 clang reports the following error:
   CC mlx5_rxmode.o
 /drivers/net/mlx5/mlx5_ethdev.c:820:32: error: field 'edata' with variable
  sized type 'struct ethtool_link_settings' not at the end of a struct or
  class is a GNU extension [-Werror,-Wgnu-variable-sized-type-not-at-end]
      struct ethtool_link_settings edata;

Use alternative approach to reserve buffer space on the stack.

Fixes: ef09a7fc7620 ("net/mlx5: fix inconsistent link status query")
Cc: gowrishankar.m@linux.vnet.ibm.com
Cc: stable@dpdk.org

Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
---
 drivers/net/mlx5/mlx5_ethdev.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/net/mlx5/mlx5_ethdev.c b/drivers/net/mlx5/mlx5_ethdev.c
index 57f6237..0d2dae4 100644
--- a/drivers/net/mlx5/mlx5_ethdev.c
+++ b/drivers/net/mlx5/mlx5_ethdev.c
@@ -49,6 +49,7 @@
 #include <linux/sockios.h>
 #include <linux/version.h>
 #include <fcntl.h>
+#include <stdalign.h>
 
 #include <rte_atomic.h>
 #include <rte_ethdev.h>
@@ -804,12 +805,11 @@ static int
 mlx5_link_update_unlocked_gs(struct rte_eth_dev *dev, int wait_to_complete)
 {
 	struct priv *priv = mlx5_get_priv(dev);
-	__extension__ struct {
-		struct ethtool_link_settings edata;
-		uint32_t link_mode_data[3 *
-					ETHTOOL_LINK_MODE_MASK_MAX_KERNEL_NU32];
-	} ecmd;
-
+	alignas(struct ethtool_link_settings)
+	uint8_t data[offsetof(struct ethtool_link_settings, link_mode_masks) +
+		     sizeof(uint32_t) *
+		     ETHTOOL_LINK_MODE_MASK_MAX_KERNEL_NU32 * 3];
+	struct ethtool_link_settings *ecmd = (void *)data;
 	struct ifreq ifr;
 	struct rte_eth_link dev_link;
 	uint64_t sc;
@@ -822,23 +822,23 @@ mlx5_link_update_unlocked_gs(struct rte_eth_dev *dev, int wait_to_complete)
 	memset(&dev_link, 0, sizeof(dev_link));
 	dev_link.link_status = ((ifr.ifr_flags & IFF_UP) &&
 				(ifr.ifr_flags & IFF_RUNNING));
-	memset(&ecmd, 0, sizeof(ecmd));
-	ecmd.edata.cmd = ETHTOOL_GLINKSETTINGS;
-	ifr.ifr_data = (void *)&ecmd;
+	memset(ecmd, 0, sizeof(*ecmd));
+	ecmd->cmd = ETHTOOL_GLINKSETTINGS;
+	ifr.ifr_data = (void *)ecmd;
 	if (priv_ifreq(priv, SIOCETHTOOL, &ifr)) {
 		DEBUG("ioctl(SIOCETHTOOL, ETHTOOL_GLINKSETTINGS) failed: %s",
 		      strerror(errno));
 		return -1;
 	}
-	ecmd.edata.link_mode_masks_nwords = -ecmd.edata.link_mode_masks_nwords;
+	ecmd->link_mode_masks_nwords = -ecmd->link_mode_masks_nwords;
 	if (priv_ifreq(priv, SIOCETHTOOL, &ifr)) {
 		DEBUG("ioctl(SIOCETHTOOL, ETHTOOL_GLINKSETTINGS) failed: %s",
 		      strerror(errno));
 		return -1;
 	}
-	dev_link.link_speed = ecmd.edata.speed;
-	sc = ecmd.edata.link_mode_masks[0] |
-		((uint64_t)ecmd.edata.link_mode_masks[1] << 32);
+	dev_link.link_speed = ecmd->speed;
+	sc = ecmd->link_mode_masks[0] |
+		((uint64_t)ecmd->link_mode_masks[1] << 32);
 	priv->link_speed_capa = 0;
 	if (sc & ETHTOOL_LINK_MODE_Autoneg_BIT)
 		priv->link_speed_capa |= ETH_LINK_SPEED_AUTONEG;
@@ -874,7 +874,7 @@ mlx5_link_update_unlocked_gs(struct rte_eth_dev *dev, int wait_to_complete)
 		  ETHTOOL_LINK_MODE_100000baseCR4_Full_BIT |
 		  ETHTOOL_LINK_MODE_100000baseLR4_ER4_Full_BIT))
 		priv->link_speed_capa |= ETH_LINK_SPEED_100G;
-	dev_link.link_duplex = ((ecmd.edata.duplex == DUPLEX_HALF) ?
+	dev_link.link_duplex = ((ecmd->duplex == DUPLEX_HALF) ?
 				ETH_LINK_HALF_DUPLEX : ETH_LINK_FULL_DUPLEX);
 	dev_link.link_autoneg = !(dev->data->dev_conf.link_speeds &
 				  ETH_LINK_SPEED_FIXED);
-- 
2.1.4