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can: add hash based access to single EFF frame filters

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In contrast to the direct access to the single SFF frame filters (which are
indexed by the SFF CAN ID itself) the single EFF frame filters are arranged
in a single linked hlist. To reduce the hlist traversal in the case of many
filter subscriptions a hash based access is introduced for single EFF filters.

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Oliver Hartkopp 2014-04-02 20:25:26 +02:00 committed by Marc Kleine-Budde
parent e3d3917f3d
commit 45c700291a
3 changed files with 75 additions and 9 deletions
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31
net/can/af_can.c
View file

@ -337,6 +337,29 @@ static struct dev_rcv_lists *find_dev_rcv_lists(struct net_device *dev)
return (struct dev_rcv_lists *)dev->ml_priv;
}
/**
* 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
@ -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++;

5
net/can/af_can.h
View file

@ -60,13 +60,16 @@ struct receiver {
};
#define CAN_SFF_RCV_ARRAY_SZ (1 << CAN_SFF_ID_BITS)
#define CAN_EFF_RCV_HASH_BITS 10
#define CAN_EFF_RCV_ARRAY_SZ (1 << CAN_EFF_RCV_HASH_BITS)
enum { RX_ERR, RX_ALL, RX_FIL, RX_INV, RX_EFF, RX_MAX };
enum { RX_ERR, RX_ALL, RX_FIL, RX_INV, RX_MAX };
/* per device receive filters linked at dev->ml_priv */
struct dev_rcv_lists {
struct hlist_head rx[RX_MAX];
struct hlist_head rx_sff[CAN_SFF_RCV_ARRAY_SZ];
struct hlist_head rx_eff[CAN_EFF_RCV_ARRAY_SZ];
int remove_on_zero_entries;
int entries;
};

48
net/can/proc.c
View file

@ -80,7 +80,6 @@ static const char rx_list_name[][8] = {
[RX_ALL] = "rx_all",
[RX_FIL] = "rx_fil",
[RX_INV] = "rx_inv",
[RX_EFF] = "rx_eff",
};
/*
@ -456,6 +455,49 @@ static const struct file_operations can_rcvlist_sff_proc_fops = {
.release = single_release,
};
static int can_rcvlist_eff_proc_show(struct seq_file *m, void *v)
{
struct net_device *dev;
struct dev_rcv_lists *d;
/* RX_EFF */
seq_puts(m, "\nreceive list 'rx_eff':\n");
rcu_read_lock();
/* eff receive list for 'all' CAN devices (dev == NULL) */
d = &can_rx_alldev_list;
can_rcvlist_proc_show_array(m, NULL, d->rx_eff, ARRAY_SIZE(d->rx_eff));
/* eff receive list for registered CAN devices */
for_each_netdev_rcu(&init_net, dev) {
if (dev->type == ARPHRD_CAN && dev->ml_priv) {
d = dev->ml_priv;
can_rcvlist_proc_show_array(m, dev, d->rx_eff,
ARRAY_SIZE(d->rx_eff));
}
}
rcu_read_unlock();
seq_putc(m, '\n');
return 0;
}
static int can_rcvlist_eff_proc_open(struct inode *inode, struct file *file)
{
return single_open(file, can_rcvlist_eff_proc_show, NULL);
}
static const struct file_operations can_rcvlist_eff_proc_fops = {
.owner = THIS_MODULE,
.open = can_rcvlist_eff_proc_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
/*
* proc utility functions
*/
@ -495,8 +537,8 @@ void can_init_proc(void)
&can_rcvlist_proc_fops, (void *)RX_FIL);
pde_rcvlist_inv = proc_create_data(CAN_PROC_RCVLIST_INV, 0644, can_dir,
&can_rcvlist_proc_fops, (void *)RX_INV);
pde_rcvlist_eff = proc_create_data(CAN_PROC_RCVLIST_EFF, 0644, can_dir,
&can_rcvlist_proc_fops, (void *)RX_EFF);
pde_rcvlist_eff = proc_create(CAN_PROC_RCVLIST_EFF, 0644, can_dir,
&can_rcvlist_eff_proc_fops);
pde_rcvlist_sff = proc_create(CAN_PROC_RCVLIST_SFF, 0644, can_dir,
&can_rcvlist_sff_proc_fops);
}