net: Fix disjunct computation of netdev features

My change

    commit e2a6b85247aacc52d6ba0d9b37a99b8d1a3e0d83
    net: Enable TSO if supported by at least one device

didn't do what was intended because the netdev_compute_features
function was designed for conjunctions.  So what happened was that
it would simply take the TSO status of the last constituent device.

This patch extends it to support both conjunctions and disjunctions
under the new name of netdev_increment_features.

It also adds a new function netdev_fix_features which does the
sanity checking that usually occurs upon registration.  This ensures
that the computation doesn't result in an illegal combination
since this checking is absent when the change is initiated via
ethtool.

The two users of netdev_compute_features have been converted.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 1 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 64875859d654..c8bcb59adfdf 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -541,6 +541,14 @@ struct net_device
 #define NETIF_F_V6_CSUM         (NETIF_F_GEN_CSUM | NETIF_F_IPV6_CSUM)
 #define NETIF_F_ALL_CSUM        (NETIF_F_V4_CSUM | NETIF_F_V6_CSUM)
 
+        /*
+         * If one device supports one of these features, then enable them
+         * for all in netdev_increment_features.
+         */
+#define NETIF_F_ONE_FOR_ALL     (NETIF_F_GSO_SOFTWARE | NETIF_F_GSO_ROBUST | \
+                                 NETIF_F_SG | NETIF_F_HIGHDMA | \
+                                 NETIF_F_FRAGLIST)
+
         /* Interface index. Unique device identifier    */
         int                     ifindex;
         int                     iflink;
@@ -1698,7 +1706,9 @@ extern char *netdev_drivername(const struct net_device *dev, char *buffer, int l
 
 extern void linkwatch_run_queue(void);
 
-extern int netdev_compute_features(unsigned long all, unsigned long one);
+unsigned long netdev_increment_features(unsigned long all, unsigned long one,
+                                        unsigned long mask);
+unsigned long netdev_fix_features(unsigned long features, const char *name);
 
 static inline int net_gso_ok(int features, int gso_type)
 {