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bonding: add bond_time_in_interval() and use it for time comparison 

Currently we use a lot of time comparison math for arp_interval
comparisons, which are sometimes quite hard to read and understand.

All the time comparisons have one pattern:
(time - arp_interval_jiffies) <= jiffies <= (time + mod *
arp_interval_jiffies + arp_interval_jiffies/2)

Introduce a new helper - bond_time_in_interval(), which will do the math in
one place and, thus, will clean up the logical code. This helper introduces
a bit of overhead (by always calculating the jiffies from arp_interval),
however it's really not visible, considering that functions using it
usually run once in arp_interval milliseconds.

There are several lines slightly over 80 chars, however breaking them would
result in more hard-to-read code than several character after the 80 mark.

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Veaceslav Falico 2013-08-03 03:50:36 +02:00 committed by David S. Miller
parent def4460cdb
commit e7f63f1dc4
1 changed files with 32 additions and 53 deletions
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85
drivers/net/bonding/bond_main.c
View File

@ -2635,6 +2635,20 @@ out_unlock:
return RX_HANDLER_ANOTHER;
}
/* function to verify if we're in the arp_interval timeslice, returns true if
* (last_act - arp_interval) <= jiffies <= (last_act + mod * arp_interval +
* arp_interval/2) . the arp_interval/2 is needed for really fast networks.
*/
static bool bond_time_in_interval(struct bonding *bond, unsigned long last_act,
int mod)
{
int delta_in_ticks = msecs_to_jiffies(bond->params.arp_interval);
return time_in_range(jiffies,
last_act - delta_in_ticks,
last_act + mod * delta_in_ticks + delta_in_ticks/2);
}
/*
* this function is called regularly to monitor each slave's link
* ensuring that traffic is being sent and received when arp monitoring
@ -2648,13 +2662,9 @@ void bond_loadbalance_arp_mon(struct work_struct *work)
arp_work.work);
struct slave *slave, *oldcurrent;
int do_failover = 0;
int delta_in_ticks, extra_ticks;
read_lock(&bond->lock);
delta_in_ticks = msecs_to_jiffies(bond->params.arp_interval);
extra_ticks = delta_in_ticks / 2;
if (list_empty(&bond->slave_list))
goto re_arm;
@ -2671,12 +2681,8 @@ void bond_loadbalance_arp_mon(struct work_struct *work)
unsigned long trans_start = dev_trans_start(slave->dev);
if (slave->link != BOND_LINK_UP) {
if (time_in_range(jiffies,
trans_start - delta_in_ticks,
trans_start + delta_in_ticks + extra_ticks) &&
time_in_range(jiffies,
slave->dev->last_rx - delta_in_ticks,
slave->dev->last_rx + delta_in_ticks + extra_ticks)) {
if (bond_time_in_interval(bond, trans_start, 1) &&
bond_time_in_interval(bond, slave->dev->last_rx, 1)) {
slave->link = BOND_LINK_UP;
bond_set_active_slave(slave);
@ -2704,12 +2710,8 @@ void bond_loadbalance_arp_mon(struct work_struct *work)
* when the source ip is 0, so don't take the link down
* if we don't know our ip yet
*/
if (!time_in_range(jiffies,
trans_start - delta_in_ticks,
trans_start + 2 * delta_in_ticks + extra_ticks) ||
!time_in_range(jiffies,
slave->dev->last_rx - delta_in_ticks,
slave->dev->last_rx + 2 * delta_in_ticks + extra_ticks)) {
if (!bond_time_in_interval(bond, trans_start, 2) ||
!bond_time_in_interval(bond, slave->dev->last_rx, 2)) {
slave->link = BOND_LINK_DOWN;
bond_set_backup_slave(slave);
@ -2749,7 +2751,8 @@ void bond_loadbalance_arp_mon(struct work_struct *work)
re_arm:
if (bond->params.arp_interval)
queue_delayed_work(bond->wq, &bond->arp_work, delta_in_ticks);
queue_delayed_work(bond->wq, &bond->arp_work,
msecs_to_jiffies(bond->params.arp_interval));
read_unlock(&bond->lock);
}
@ -2762,33 +2765,21 @@ re_arm:
*
* Called with bond->lock held for read.
*/
static int bond_ab_arp_inspect(struct bonding *bond, int delta_in_ticks)
static int bond_ab_arp_inspect(struct bonding *bond)
{
unsigned long trans_start, last_rx;
struct slave *slave;
int extra_ticks;
int commit = 0;
/* All the time comparisons below need some extra time. Otherwise, on
* fast networks the ARP probe/reply may arrive within the same jiffy
* as it was sent. Then, the next time the ARP monitor is run, one
* arp_interval will already have passed in the comparisons.
*/
extra_ticks = delta_in_ticks / 2;
bond_for_each_slave(bond, slave) {
slave->new_link = BOND_LINK_NOCHANGE;
last_rx = slave_last_rx(bond, slave);
if (slave->link != BOND_LINK_UP) {
if (time_in_range(jiffies,
last_rx - delta_in_ticks,
last_rx + delta_in_ticks + extra_ticks)) {
if (bond_time_in_interval(bond, last_rx, 1)) {
slave->new_link = BOND_LINK_UP;
commit++;
}
continue;
}
@ -2797,9 +2788,7 @@ static int bond_ab_arp_inspect(struct bonding *bond, int delta_in_ticks)
* active. This avoids bouncing, as the last receive
* times need a full ARP monitor cycle to be updated.
*/
if (time_in_range(jiffies,
slave->jiffies - delta_in_ticks,
slave->jiffies + 2 * delta_in_ticks + extra_ticks))
if (bond_time_in_interval(bond, slave->jiffies, 2))
continue;
/*
@ -2817,10 +2806,7 @@ static int bond_ab_arp_inspect(struct bonding *bond, int delta_in_ticks)
*/
if (!bond_is_active_slave(slave) &&
!bond->current_arp_slave &&
!time_in_range(jiffies,
last_rx - delta_in_ticks,
last_rx + 3 * delta_in_ticks + extra_ticks)) {
!bond_time_in_interval(bond, last_rx, 3)) {
slave->new_link = BOND_LINK_DOWN;
commit++;
}
@ -2833,13 +2819,8 @@ static int bond_ab_arp_inspect(struct bonding *bond, int delta_in_ticks)
*/
trans_start = dev_trans_start(slave->dev);
if (bond_is_active_slave(slave) &&
(!time_in_range(jiffies,
trans_start - delta_in_ticks,
trans_start + 2 * delta_in_ticks + extra_ticks) ||
!time_in_range(jiffies,
last_rx - delta_in_ticks,
last_rx + 2 * delta_in_ticks + extra_ticks))) {
(!bond_time_in_interval(bond, trans_start, 2) ||
!bond_time_in_interval(bond, last_rx, 2))) {
slave->new_link = BOND_LINK_DOWN;
commit++;
}
@ -2854,7 +2835,7 @@ static int bond_ab_arp_inspect(struct bonding *bond, int delta_in_ticks)
*
* Called with RTNL and bond->lock for read.
*/
static void bond_ab_arp_commit(struct bonding *bond, int delta_in_ticks)
static void bond_ab_arp_commit(struct bonding *bond)
{
unsigned long trans_start;
struct slave *slave;
@ -2866,11 +2847,9 @@ static void bond_ab_arp_commit(struct bonding *bond, int delta_in_ticks)
case BOND_LINK_UP:
trans_start = dev_trans_start(slave->dev);
if ((!bond->curr_active_slave &&
time_in_range(jiffies,
trans_start - delta_in_ticks,
trans_start + delta_in_ticks + delta_in_ticks / 2)) ||
bond->curr_active_slave != slave) {
if (bond->curr_active_slave != slave ||
(!bond->curr_active_slave &&
bond_time_in_interval(bond, trans_start, 1))) {
slave->link = BOND_LINK_UP;
if (bond->current_arp_slave) {
bond_set_slave_inactive_flags(
@ -3011,7 +2990,7 @@ void bond_activebackup_arp_mon(struct work_struct *work)
should_notify_peers = bond_should_notify_peers(bond);
if (bond_ab_arp_inspect(bond, delta_in_ticks)) {
if (bond_ab_arp_inspect(bond)) {
read_unlock(&bond->lock);
/* Race avoidance with bond_close flush of workqueue */
@ -3024,7 +3003,7 @@ void bond_activebackup_arp_mon(struct work_struct *work)
read_lock(&bond->lock);
bond_ab_arp_commit(bond, delta_in_ticks);
bond_ab_arp_commit(bond);
read_unlock(&bond->lock);
rtnl_unlock();