bonding: Fix jiffies overflow problems (again)

The time_before_eq()/time_after_eq() functions operate on unsigned
long and only work if the difference between the two compared values
is smaller than half the range of unsigned long (31 bits on i386).

Some of the variables (slave->jiffies, dev->trans_start, dev->last_rx)
used by bonding store a copy of jiffies and may not be updated for a
long time. With HZ=1000, time_before_eq()/time_after_eq() will start
giving bad results after ~25 days.

jiffies will never be before slave->jiffies, dev->trans_start,
dev->last_rx by more than possibly a couple ticks caused by preemption
of this code. This allows us to detect/prevent these overflows by
replacing time_before_eq()/time_after_eq() with time_in_range().

Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 2cc4cfc31892cd85458dec20b6c46401fdb90d9b..3b16f62d5606c741e97fb0a7c7b0b211c903157d 100644 (file)
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -2797,9 +2797,15 @@ void bond_loadbalance_arp_mon(struct work_struct *work)
         *       so it can wait
         */
        bond_for_each_slave(bond, slave, i) {
+               unsigned long trans_start = dev_trans_start(slave->dev);
+
                if (slave->link != BOND_LINK_UP) {
-                       if (time_before_eq(jiffies, dev_trans_start(slave->dev) + delta_in_ticks) &&
-                           time_before_eq(jiffies, slave->dev->last_rx + delta_in_ticks)) {
+                       if (time_in_range(jiffies,
+                               trans_start - delta_in_ticks,
+                               trans_start + delta_in_ticks) &&
+                           time_in_range(jiffies,
+                               slave->dev->last_rx - delta_in_ticks,
+                               slave->dev->last_rx + delta_in_ticks)) {
 
                                slave->link  = BOND_LINK_UP;
                                slave->state = BOND_STATE_ACTIVE;
@@ -2827,8 +2833,12 @@ 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_after_eq(jiffies, dev_trans_start(slave->dev) + 2*delta_in_ticks) ||
-                           (time_after_eq(jiffies, slave->dev->last_rx + 2*delta_in_ticks))) {
+                       if (!time_in_range(jiffies,
+                               trans_start - delta_in_ticks,
+                               trans_start + 2 * delta_in_ticks) ||
+                           !time_in_range(jiffies,
+                               slave->dev->last_rx - delta_in_ticks,
+                               slave->dev->last_rx + 2 * delta_in_ticks)) {
 
                                slave->link  = BOND_LINK_DOWN;
                                slave->state = BOND_STATE_BACKUP;
@@ -2883,13 +2893,16 @@ static int bond_ab_arp_inspect(struct bonding *bond, int delta_in_ticks)
 {
        struct slave *slave;
        int i, commit = 0;
+       unsigned long trans_start;
 
        bond_for_each_slave(bond, slave, i) {
                slave->new_link = BOND_LINK_NOCHANGE;
 
                if (slave->link != BOND_LINK_UP) {
-                       if (time_before_eq(jiffies, slave_last_rx(bond, slave) +
-                                          delta_in_ticks)) {
+                       if (time_in_range(jiffies,
+                               slave_last_rx(bond, slave) - delta_in_ticks,
+                               slave_last_rx(bond, slave) + delta_in_ticks)) {
+
                                slave->new_link = BOND_LINK_UP;
                                commit++;
                        }
@@ -2902,8 +2915,9 @@ 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_after_eq(jiffies, slave->jiffies +
-                                  2 * delta_in_ticks))
+               if (time_in_range(jiffies,
+                                 slave->jiffies - delta_in_ticks,
+                                 slave->jiffies + 2 * delta_in_ticks))
                        continue;
 
                /*
@@ -2921,8 +2935,10 @@ static int bond_ab_arp_inspect(struct bonding *bond, int delta_in_ticks)
                 */
                if (slave->state == BOND_STATE_BACKUP &&
                    !bond->current_arp_slave &&
-                   time_after(jiffies, slave_last_rx(bond, slave) +
-                              3 * delta_in_ticks)) {
+                   !time_in_range(jiffies,
+                       slave_last_rx(bond, slave) - delta_in_ticks,
+                       slave_last_rx(bond, slave) + 3 * delta_in_ticks)) {
+
                        slave->new_link = BOND_LINK_DOWN;
                        commit++;
                }
@@ -2933,11 +2949,15 @@ static int bond_ab_arp_inspect(struct bonding *bond, int delta_in_ticks)
                 * - (more than 2*delta since receive AND
                 *    the bond has an IP address)
                 */
+               trans_start = dev_trans_start(slave->dev);
                if ((slave->state == BOND_STATE_ACTIVE) &&
-                   (time_after_eq(jiffies, dev_trans_start(slave->dev) +
-                                   2 * delta_in_ticks) ||
-                     (time_after_eq(jiffies, slave_last_rx(bond, slave)
-                                    + 2 * delta_in_ticks)))) {
+                   (!time_in_range(jiffies,
+                       trans_start - delta_in_ticks,
+                       trans_start + 2 * delta_in_ticks) ||
+                    !time_in_range(jiffies,
+                       slave_last_rx(bond, slave) - delta_in_ticks,
+                       slave_last_rx(bond, slave) + 2 * delta_in_ticks))) {
+
                        slave->new_link = BOND_LINK_DOWN;
                        commit++;
                }
@@ -2956,6 +2976,7 @@ static void bond_ab_arp_commit(struct bonding *bond, int delta_in_ticks)
 {
        struct slave *slave;
        int i;
+       unsigned long trans_start;
 
        bond_for_each_slave(bond, slave, i) {
                switch (slave->new_link) {
@@ -2963,10 +2984,11 @@ static void bond_ab_arp_commit(struct bonding *bond, int delta_in_ticks)
                        continue;
 
                case BOND_LINK_UP:
+                       trans_start = dev_trans_start(slave->dev);
                        if ((!bond->curr_active_slave &&
-                            time_before_eq(jiffies,
-                                           dev_trans_start(slave->dev) +
-                                           delta_in_ticks)) ||
+                            time_in_range(jiffies,
+                                          trans_start - delta_in_ticks,
+                                          trans_start + delta_in_ticks)) ||
                            bond->curr_active_slave != slave) {
                                slave->link = BOND_LINK_UP;
                                bond->current_arp_slave = NULL;