net: Dont use ifindices in hash fns
Eric noticed, that when there will be devices with equal indices, some
hash functions that use them will become less effective as they could.
Fix this in advance by mixing the net_device address into the hash value
instead of the device index.
This is true for arp and ndisc hash fns. The netlabel, can and llc ones
are also ifindex-based, but that three are init_net-only, thus will not
be affected.
Many thanks to David and Eric for the hash32_ptr implementation!
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/arp.h b/include/net/arp.h
index 7f7df93..b630dae 100644
--- a/include/net/arp.h
+++ b/include/net/arp.h
@@ -3,6 +3,7 @@
#define _ARP_H
#include <linux/if_arp.h>
+#include <linux/hash.h>
#include <net/neighbour.h>
@@ -10,7 +11,7 @@
static inline u32 arp_hashfn(u32 key, const struct net_device *dev, u32 hash_rnd)
{
- u32 val = key ^ dev->ifindex;
+ u32 val = key ^ hash32_ptr(dev);
return val * hash_rnd;
}