diff options
| author | Qingfang Deng <qingfang.deng@linux.dev> | 2026-04-29 10:38:46 +0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-05-01 18:45:16 -0700 |
| commit | ff393252f99f261ba885f05fbfdfe89807c7ffd3 (patch) | |
| tree | 0a4bbd3b77e2f96400ad557f4a053d264508ed4d | |
| parent | 286efd34d1a1ef5d83f9441b5e59421a26738169 (diff) | |
pppoe: optimize hash with word access
Currently, hash_item() processes the 6-byte Ethernet address and the
2-byte session ID byte-wise to compute a hash.
Optimize this by using 16-bit word operations: XOR three 16-bit words
from the Ethernet address and the 16-bit session ID, then fold the
result. This reduces the total number of loads and XORs. The Ethernet
addresses in a skb and struct pppoe_addr are both 2-byte aligned, so the
u16 pointer cast is safe.
Signed-off-by: Qingfang Deng <qingfang.deng@linux.dev>
Link: https://patch.msgid.link/20260429023848.153425-1-qingfang.deng@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | drivers/net/ppp/pppoe.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/drivers/net/ppp/pppoe.c b/drivers/net/ppp/pppoe.c index bdd61c504a1c..ad5bb98c1579 100644 --- a/drivers/net/ppp/pppoe.c +++ b/drivers/net/ppp/pppoe.c @@ -136,15 +136,15 @@ static inline int cmp_addr(struct pppoe_addr *a, __be16 sid, char *addr) #error 8 must be a multiple of PPPOE_HASH_BITS #endif -static int hash_item(__be16 sid, unsigned char *addr) +static u8 hash_item(__be16 sid, const u8 addr[ETH_ALEN]) { - unsigned char hash = 0; + const u16 *addr16 = (const u16 *)addr; unsigned int i; + u16 hash16; + u8 hash; - for (i = 0; i < ETH_ALEN; i++) - hash ^= addr[i]; - for (i = 0; i < sizeof(sid_t) * 8; i += 8) - hash ^= (__force __u32)sid >> i; + hash16 = addr16[0] ^ addr16[1] ^ addr16[2] ^ (__force u16)sid; + hash = (hash16 >> 8) ^ hash16; for (i = 8; (i >>= 1) >= PPPOE_HASH_BITS;) hash ^= hash >> i; |