[PATCH net] netdevice.h: Fix unintentional disable of ALL_FOR_ALL features on upper device

From: Tariq Toukan <tariqt@nvidia.com>
To: "David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Eric Dumazet <edumazet@google.com>,
	Herbert Xu <herbert@gondor.apana.org.au>
Cc: netdev@vger.kernel.org, Moshe Shemesh <moshe@nvidia.com>,
	Tariq Toukan <ttoukan.linux@gmail.com>,
	Maxim Mikityanskiy <maximmi@nvidia.com>,
	Saeed Mahameed <saeedm@nvidia.com>,
	Tariq Toukan <tariqt@nvidia.com>
Subject: [PATCH net] netdevice.h: Fix unintentional disable of ALL_FOR_ALL features on upper device
Date: Mon, 23 Nov 2020 16:12:56 +0200	[thread overview]
Message-ID: <20201123141256.14208-1-tariqt@nvidia.com> (raw)

Calling netdev_increment_features() on upper/master device from
netdev_add_tso_features() implies unintentional clearance of ALL_FOR_ALL
features supported by all slaves.  Fix it by passing ALL_FOR_ALL in
addition to ALL_TSO.

Fixes: b0ce3508b25e ("bonding: allow TSO being set on bonding master")
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 include/linux/netdevice.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Hi,

I know that netdev_increment_features() does not set any feature that's
unmasked in the mask argument.
I wonder why it can clear them though, was it meant to be like this?
If not, then the proper fix should be in netdev_increment_features(), not
in netdev_add_tso_features().

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 18dec08439f9..a9d5e4bb829b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -4748,7 +4748,7 @@ netdev_features_t netdev_increment_features(netdev_features_t all,
 static inline netdev_features_t netdev_add_tso_features(netdev_features_t features,
 							netdev_features_t mask)
 {
-	return netdev_increment_features(features, NETIF_F_ALL_TSO, mask);
+	return netdev_increment_features(features, NETIF_F_ALL_TSO | NETIF_F_ALL_FOR_ALL, mask);
 }
 
 int __netdev_update_features(struct net_device *dev);
-- 
2.21.0

