The features attribute is of type u64 and stored in the native endianes on the system. The for_each_set_bit() macro takes a pointer to a 32 bit array and goes over the bits in this area. On little Endian systems this also works with an u64 as the most significant bit is on the highest address, but on big endian the words are swapped. When we expect bit 15 here we get bit 47 (15 + 32).

This patch converts it more or less to its own for_each_set_bit() implementation which works on 64 bit integers directly. This is then completely in host endianness and should work like expected.

Fixes: fd867d51f ("net/core: generic support for disabling netdev features down stack") Cc: stable@vger.kernel.org Signed-off-by: Hauke Mehrtens hauke.mehrtens@intel.com --- include/linux/netdev_features.h | 23 +++++++++++++++++++++-- net/core/dev.c | 4 ++-- 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/include/linux/netdev_features.h b/include/linux/netdev_features.h index 2b2a6dc..fce2856 100644 --- a/include/linux/netdev_features.h +++ b/include/linux/netdev_features.h @@ -11,6 +11,7 @@ #define _LINUX_NETDEV_FEATURES_H

#include <linux/types.h> +#include <asm/byteorder.h>

typedef u64 netdev_features_t;

@@ -154,8 +155,26 @@ enum { #define NETIF_F_HW_TLS_TX __NETIF_F(HW_TLS_TX) #define NETIF_F_HW_TLS_RX __NETIF_F(HW_TLS_RX)

-#define for_each_netdev_feature(mask_addr, bit) \ - for_each_set_bit(bit, (unsigned long *)mask_addr, NETDEV_FEATURE_COUNT) +/* Finds the next feature with the highest number of the range of start till 0. + */ +static inline int find_next_netdev_feature(u64 feature, unsigned long start) +{ + /* like BITMAP_LAST_WORD_MASK() for u64 + * this sets the most significant 64 - start to 0. + */ + feature &= ~0ULL >> (-start & ((sizeof(feature) * 8) - 1)); + + return fls64(feature) - 1; +} + +/* This goes for the MSB to the LSB through the set feature bits, + * mask_addr should be a u64 and bit an int + */ +#define for_each_netdev_feature(mask_addr, bit) \ + for ((bit) = find_next_netdev_feature((mask_addr), \ + NETDEV_FEATURE_COUNT); \ + (bit) >= 0; \ + (bit) = find_next_netdev_feature((mask_addr), (bit) - 1))

/* Features valid for ethtool to change */ /* = all defined minus driver/device-class-related */ diff --git a/net/core/dev.c b/net/core/dev.c index 8e276e0..5d03889 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -8152,7 +8152,7 @@ static netdev_features_t netdev_sync_upper_features(struct net_device *lower, netdev_features_t feature; int feature_bit;

- for_each_netdev_feature(&upper_disables, feature_bit) { + for_each_netdev_feature(upper_disables, feature_bit) { feature = __NETIF_F_BIT(feature_bit); if (!(upper->wanted_features & feature) && (features & feature)) { @@ -8172,7 +8172,7 @@ static void netdev_sync_lower_features(struct net_device *upper, netdev_features_t feature; int feature_bit;

- for_each_netdev_feature(&upper_disables, feature_bit) { + for_each_netdev_feature(upper_disables, feature_bit) { feature = __NETIF_F_BIT(feature_bit); if (!(features & feature) && (lower->features & feature)) { netdev_dbg(upper, "Disabling feature %pNF on lower dev %s.\n",