diff options
Diffstat (limited to 'net/can/af_can.c')
| -rw-r--r-- | net/can/af_can.c | 31 |
1 files changed, 26 insertions, 5 deletions
diff --git a/net/can/af_can.c b/net/can/af_can.c index a27f8aad9e99..ce82337521f6 100644 --- a/net/can/af_can.c +++ b/net/can/af_can.c @@ -338,6 +338,29 @@ static struct dev_rcv_lists *find_dev_rcv_lists(struct net_device *dev) } /** + * effhash - hash function for 29 bit CAN identifier reduction + * @can_id: 29 bit CAN identifier + * + * Description: + * To reduce the linear traversal in one linked list of _single_ EFF CAN + * frame subscriptions the 29 bit identifier is mapped to 10 bits. + * (see CAN_EFF_RCV_HASH_BITS definition) + * + * Return: + * Hash value from 0x000 - 0x3FF ( enforced by CAN_EFF_RCV_HASH_BITS mask ) + */ +static unsigned int effhash(canid_t can_id) +{ + unsigned int hash; + + hash = can_id; + hash ^= can_id >> CAN_EFF_RCV_HASH_BITS; + hash ^= can_id >> (2 * CAN_EFF_RCV_HASH_BITS); + + return hash & ((1 << CAN_EFF_RCV_HASH_BITS) - 1); +} + +/** * find_rcv_list - determine optimal filterlist inside device filter struct * @can_id: pointer to CAN identifier of a given can_filter * @mask: pointer to CAN mask of a given can_filter @@ -400,10 +423,8 @@ static struct hlist_head *find_rcv_list(canid_t *can_id, canid_t *mask, !(*can_id & CAN_RTR_FLAG)) { if (*can_id & CAN_EFF_FLAG) { - if (*mask == (CAN_EFF_MASK | CAN_EFF_RTR_FLAGS)) { - /* RFC: a future use-case for hash-tables? */ - return &d->rx[RX_EFF]; - } + if (*mask == (CAN_EFF_MASK | CAN_EFF_RTR_FLAGS)) + return &d->rx_eff[effhash(*can_id)]; } else { if (*mask == (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS)) return &d->rx_sff[*can_id]; @@ -632,7 +653,7 @@ static int can_rcv_filter(struct dev_rcv_lists *d, struct sk_buff *skb) return matches; if (can_id & CAN_EFF_FLAG) { - hlist_for_each_entry_rcu(r, &d->rx[RX_EFF], list) { + hlist_for_each_entry_rcu(r, &d->rx_eff[effhash(can_id)], list) { if (r->can_id == can_id) { deliver(skb, r); matches++; |