bonding: Send more than one gratuitous ARP when slave takes over

With IPoIB, reception of gratuitous ARP by neighboring hosts
is essential for a successful change of slaves in case of failure.
Otherwise, they won't learn about the HW address change and need
to wait a long time until the neighboring system gives up and sends
an ARP request to learn the new HW address.  This patch decreases
the chance for a lost of a gratuitous ARP packet by sending it more
than once. The number retries is configurable and can be set with a
module param.

Signed-off-by: Moni Shoua <monis@voltaire.com>
Acked-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 2a0039f193770d677a63fef13be00aa744f7a79e..fa3c2101fe750d48379f0083e37a35a2737f0389 100644 (file)
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -88,6 +88,7 @@
 #define BOND_LINK_ARP_INTERV   0
 
 static int max_bonds   = BOND_DEFAULT_MAX_BONDS;
+static int num_grat_arp = 1;
 static int miimon      = BOND_LINK_MON_INTERV;
 static int updelay     = 0;
 static int downdelay   = 0;
@@ -104,6 +105,8 @@ struct bond_params bonding_defaults;
 
 module_param(max_bonds, int, 0);
 MODULE_PARM_DESC(max_bonds, "Max number of bonded devices");
+module_param(num_grat_arp, int, 0644);
+MODULE_PARM_DESC(num_grat_arp, "Number of gratuitous ARP packets to send on failover event");
 module_param(miimon, int, 0);
 MODULE_PARM_DESC(miimon, "Link check interval in milliseconds");
 module_param(updelay, int, 0);
@@ -1109,14 +1112,18 @@ void bond_change_active_slave(struct bonding *bond, struct slave *new_active)
                if (new_active && bond->params.fail_over_mac)
                        memcpy(bond->dev->dev_addr,  new_active->dev->dev_addr,
                                new_active->dev->addr_len);
+               bond->send_grat_arp = bond->params.num_grat_arp;
                if (bond->curr_active_slave &&
                        test_bit(__LINK_STATE_LINKWATCH_PENDING,
                                        &bond->curr_active_slave->dev->state)) {
                        dprintk("delaying gratuitous arp on %s\n",
                                bond->curr_active_slave->dev->name);
-                       bond->send_grat_arp = 1;
-               } else
-                       bond_send_gratuitous_arp(bond);
+               } else {
+                       if (bond->send_grat_arp > 0) {
+                               bond_send_gratuitous_arp(bond);
+                               bond->send_grat_arp--;
+                       }
+               }
        }
 }
 
@@ -2144,7 +2151,7 @@ static int __bond_mii_monitor(struct bonding *bond, int have_locks)
                        dprintk("sending delayed gratuitous arp on on %s\n",
                                bond->curr_active_slave->dev->name);
                        bond_send_gratuitous_arp(bond);
-                       bond->send_grat_arp = 0;
+                       bond->send_grat_arp--;
                }
        }
        read_lock(&bond->curr_slave_lock);
@@ -4626,6 +4633,13 @@ static int bond_check_params(struct bond_params *params)
                use_carrier = 1;
        }
 
+       if (num_grat_arp < 0 || num_grat_arp > 255) {
+               printk(KERN_WARNING DRV_NAME
+                      ": Warning: num_grat_arp (%d) not in range 0-255 so it "
+                      "was reset to 1 \n", num_grat_arp);
+               num_grat_arp = 1;
+       }
+
        /* reset values for 802.3ad */
        if (bond_mode == BOND_MODE_8023AD) {
                if (!miimon) {
@@ -4813,6 +4827,7 @@ static int bond_check_params(struct bond_params *params)
        params->mode = bond_mode;
        params->xmit_policy = xmit_hashtype;
        params->miimon = miimon;
+       params->num_grat_arp = num_grat_arp;
        params->arp_interval = arp_interval;
        params->arp_validate = arp_validate_value;
        params->updelay = updelay;

diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index 1f028579e53bd8d1da2db99be549734d0577f396..7a61e9a143863ae6c5d3387bba815b74796ba9e4 100644 (file)
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -950,6 +950,45 @@ out:
 }
 static DEVICE_ATTR(lacp_rate, S_IRUGO | S_IWUSR, bonding_show_lacp, bonding_store_lacp);
 
+/*
+ * Show and set the number of grat ARP to send after a failover event.
+ */
+static ssize_t bonding_show_n_grat_arp(struct device *d,
+                                  struct device_attribute *attr,
+                                  char *buf)
+{
+       struct bonding *bond = to_bond(d);
+
+       return sprintf(buf, "%d\n", bond->params.num_grat_arp);
+}
+
+static ssize_t bonding_store_n_grat_arp(struct device *d,
+                                   struct device_attribute *attr,
+                                   const char *buf, size_t count)
+{
+       int new_value, ret = count;
+       struct bonding *bond = to_bond(d);
+
+       if (sscanf(buf, "%d", &new_value) != 1) {
+               printk(KERN_ERR DRV_NAME
+                      ": %s: no num_grat_arp value specified.\n",
+                      bond->dev->name);
+               ret = -EINVAL;
+               goto out;
+       }
+       if (new_value < 0 || new_value > 255) {
+               printk(KERN_ERR DRV_NAME
+                      ": %s: Invalid num_grat_arp value %d not in range 0-255; rejected.\n",
+                      bond->dev->name, new_value);
+               ret = -EINVAL;
+               goto out;
+       } else {
+               bond->params.num_grat_arp = new_value;
+       }
+out:
+       return ret;
+}
+static DEVICE_ATTR(num_grat_arp, S_IRUGO | S_IWUSR, bonding_show_n_grat_arp, bonding_store_n_grat_arp);
 /*
  * Show and set the MII monitor interval.  There are two tricky bits
  * here.  First, if MII monitoring is activated, then we must disable
@@ -1387,6 +1426,7 @@ static struct attribute *per_bond_attrs[] = {
        &dev_attr_updelay.attr,
        &dev_attr_lacp_rate.attr,
        &dev_attr_xmit_hash_policy.attr,
+       &dev_attr_num_grat_arp.attr,
        &dev_attr_miimon.attr,
        &dev_attr_primary.attr,
        &dev_attr_use_carrier.attr,

diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index 0ce7f4ae920f3e85d30edb550845db06d2bf9b7a..46a2ed507b3325f3c9d842bed936c921dcb9a7a7 100644 (file)
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -125,6 +125,7 @@ struct bond_params {
        int mode;
        int xmit_policy;
        int miimon;
+       int num_grat_arp;
        int arp_interval;
        int arp_validate;
        int use_carrier;