Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit f1543f8b authored by Florian Zumbiehl's avatar Florian Zumbiehl Committed by David S. Miller
Browse files

[PPPOE]: Improve hashing function in hash_item(). 



The new code produces the same results as the old version and is
~ 3 to 6 times faster for 4-bit hashes on the CPUs I tested.

Signed-off-by: default avatarFlorian Zumbiehl <florz@florz.de>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 48b8d783

drivers/net/pppoe.c

+15 −10
Original line number Diff line number Diff line
@@ -108,19 +108,24 @@ static inline int cmp_addr(struct pppoe_addr *a, unsigned long sid, char *addr) 
		(memcmp(a->remote,addr,ETH_ALEN) == 0));

}



static int hash_item(unsigned long sid, unsigned char *addr)

#if 8%PPPOE_HASH_BITS

#error 8 must be a multiple of PPPOE_HASH_BITS

#endif



static int hash_item(unsigned int sid, unsigned char *addr)

{

	char hash = 0;

	int i, j;

	unsigned char hash = 0;

	unsigned int i;



	for (i = 0; i < ETH_ALEN ; ++i) {

		for (j = 0; j < 8/PPPOE_HASH_BITS ; ++j) {

			hash ^= addr[i] >> ( j * PPPOE_HASH_BITS );

	for (i = 0 ; i < ETH_ALEN ; i++) {

		hash ^= addr[i];

	}

	for (i = 0 ; i < sizeof(sid_t)*8 ; i += 8 ){

		hash ^= sid>>i;

	}

	for (i = 8 ; (i>>=1) >= PPPOE_HASH_BITS ; ) {

		hash ^= hash>>i;

	}



	for (i = 0; i < (sizeof(unsigned long)*8) / PPPOE_HASH_BITS ; ++i)

		hash ^= sid >> (i*PPPOE_HASH_BITS);



	return hash & ( PPPOE_HASH_SIZE - 1 );

}