net: Fix features skip in for_each_netdev_feature()

[ Upstream commit 85db635 ]

The find_next_netdev_feature() macro gets the "remaining length",
not bit index.
Passing "bit - 1" for the following iteration is wrong as it skips
the adjacent bit. Pass "bit" instead.

Fixes: 3b89ea9 ("net: Fix for_each_netdev_feature on Big endian")
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Gal Pressman <gal@nvidia.com>
Link: https://lore.kernel.org/r/20220504080914.1918-1-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

include/linux/netdev_features.h

@@ -158,7 +158,7 @@ enum {
 #define NETIF_F_GSO_FRAGLIST	__NETIF_F(GSO_FRAGLIST)
 #define NETIF_F_HW_MACSEC	__NETIF_F(HW_MACSEC)
 
-/* Finds the next feature with the highest number of the range of start till 0.
+/* Finds the next feature with the highest number of the range of start-1 till 0.
  */
 static inline int find_next_netdev_feature(u64 feature, unsigned long start)
 {
@@ -177,7 +177,7 @@ static inline int find_next_netdev_feature(u64 feature, unsigned long start)
 	for ((bit) = find_next_netdev_feature((mask_addr),		\
 					      NETDEV_FEATURE_COUNT);	\
 	     (bit) >= 0;						\
-	     (bit) = find_next_netdev_feature((mask_addr), (bit) - 1))
+	     (bit) = find_next_netdev_feature((mask_addr), (bit)))
 
 /* Features valid for ethtool to change */
 /* = all defined minus driver/device-class-related */