bonding: add an option to fail when any of arp_ip_target is inaccessible

Currently, we fail only when all of the ips in arp_ip_target are gone.
However, in some situations we might need to fail if even one host from
arp_ip_target becomes unavailable.

All situations, obviously, rely on the idea that we need *completely*
functional network, with all interfaces/addresses working correctly.

One real world example might be:
vlans on top on bond (hybrid port). If bond and vlans have ips assigned
and we have their peers monitored via arp_ip_target - in case of switch
misconfiguration (trunk/access port), slave driver malfunction or
tagged/untagged traffic dropped on the way - we will be able to switch
to another slave.

Though any other configuration needs that if we need to have access to all
arp_ip_targets.

This patch adds this possibility by adding a new parameter -
arp_all_targets (both as a module parameter and as a sysfs knob). It can be
set to:

	0 or any (the default) - which works exactly as it's working now -
	the slave is up if any of the arp_ip_targets are up.

	1 or all - the slave is up if all of the arp_ip_targets are up.

This parameter can be changed on the fly (via sysfs), and requires the mode
to be active-backup and arp_validate to be enabled (it obeys the
arp_validate config on which slaves to validate).

Internally it's done through:

1) Add target_last_arp_rx[BOND_MAX_ARP_TARGETS] array to slave struct. It's
   an array of jiffies, meaning that slave->target_last_arp_rx[i] is the
   last time we've received arp from bond->params.arp_targets[i] on this
   slave.

2) If we successfully validate an arp from bond->params.arp_targets[i] in
   bond_validate_arp() - update the slave->target_last_arp_rx[i] with the
   current jiffies value.

3) When getting slave's last_rx via slave_last_rx(), we return the oldest
   time when we've received an arp from any address in
   bond->params.arp_targets[].

If the value of arp_all_targets == 0 - we still work the same way as
before.

Also, update the documentation to reflect the new parameter.

v3->v4:
Kill the forgotten rtnl_unlock(), rephrase the documentation part to be
more clear, don't fail setting arp_all_targets if arp_validate is not set -
it has no effect anyway but can be easier to set up. Also, print a warning
if the last arp_ip_target is removed while the arp_interval is on, but not
the arp_validate.

v2->v3:
Use _bh spinlock, remove useless rtnl_lock() and use jiffies for new
arp_ip_target last arp, instead of slave_last_rx(). On bond_enslave(),
use the same initialization value for target_last_arp_rx[] as is used
for the default last_arp_rx, to avoid useless interface flaps.

Also, instead of failing to remove the last arp_ip_target just print a
warning - otherwise it might break existing scripts.

v1->v2:
Correctly handle adding/removing hosts in arp_ip_target - we need to
shift/initialize all slave's target_last_arp_rx. Also, don't fail module
loading on arp_all_targets misconfiguration, just disable it, and some
minor style fixes.

Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 28 insertions, 2 deletions

diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index 486e532f77e4..3fb73cc8c34a 100644
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -144,6 +144,7 @@ struct bond_params {
         u8 num_peer_notif;
         int arp_interval;
         int arp_validate;
+        int arp_all_targets;
         int use_carrier;
         int fail_over_mac;
         int updelay;
@@ -179,6 +180,7 @@ struct slave {
         int    delay;
         unsigned long jiffies;
         unsigned long last_arp_rx;
+        unsigned long target_last_arp_rx[BOND_MAX_ARP_TARGETS];
         s8     link;    /* one of BOND_LINK_XXXX */
         s8     new_link;
         u8     backup:1,   /* indicates backup slave. Value corresponds with
@@ -322,6 +324,9 @@ static inline bool bond_is_active_slave(struct slave *slave)
 #define BOND_FOM_ACTIVE                 1
 #define BOND_FOM_FOLLOW                 2
 
+#define BOND_ARP_TARGETS_ANY            0
+#define BOND_ARP_TARGETS_ALL            1
+
 #define BOND_ARP_VALIDATE_NONE          0
 #define BOND_ARP_VALIDATE_ACTIVE        (1 << BOND_STATE_ACTIVE)
 #define BOND_ARP_VALIDATE_BACKUP        (1 << BOND_STATE_BACKUP)
@@ -334,11 +339,31 @@ static inline int slave_do_arp_validate(struct bonding *bond,
         return bond->params.arp_validate & (1 << bond_slave_state(slave));
 }
 
+/* Get the oldest arp which we've received on this slave for bond's
+ * arp_targets.
+ */
+static inline unsigned long slave_oldest_target_arp_rx(struct bonding *bond,
+                                                       struct slave *slave)
+{
+        int i = 1;
+        unsigned long ret = slave->target_last_arp_rx[0];
+
+        for (; (i < BOND_MAX_ARP_TARGETS) && bond->params.arp_targets[i]; i++)
+                if (time_before(slave->target_last_arp_rx[i], ret))
+                        ret = slave->target_last_arp_rx[i];
+
+        return ret;
+}
+
 static inline unsigned long slave_last_rx(struct bonding *bond,
                                         struct slave *slave)
 {
-        if (slave_do_arp_validate(bond, slave))
-                return slave->last_arp_rx;
+        if (slave_do_arp_validate(bond, slave)) {
+                if (bond->params.arp_all_targets == BOND_ARP_TARGETS_ALL)
+                        return slave_oldest_target_arp_rx(bond, slave);
+                else
+                        return slave->last_arp_rx;
+        }
 
         return slave->dev->last_rx;
 }
@@ -486,6 +511,7 @@ extern const struct bond_parm_tbl bond_lacp_tbl[];
 extern const struct bond_parm_tbl bond_mode_tbl[];
 extern const struct bond_parm_tbl xmit_hashtype_tbl[];
 extern const struct bond_parm_tbl arp_validate_tbl[];
+extern const struct bond_parm_tbl arp_all_targets_tbl[];
 extern const struct bond_parm_tbl fail_over_mac_tbl[];
 extern const struct bond_parm_tbl pri_reselect_tbl[];
 extern struct bond_parm_tbl ad_select_tbl[];