bonding: add retransmit membership reports tunable

Allow sysadmins to configure the number of multicast
membership report sent on a link failure event.

Signed-off-by: Flavio Leitner <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

Documentation/networking/bonding.txt

···
 	does not exist, and the layer2 policy is the only policy.  The
 	layer2+3 value was added for bonding version 3.2.2.
 
+resend_igmp
+
+	Specifies the number of IGMP membership reports to be issued after
+	a failover event. One membership report is issued immediately after
+	the failover, subsequent packets are sent in each 200ms interval.
+
+	The valid range is 0 - 255; the default value is 1. This option
+	was added for bonding version 3.7.0.
 
 3. Configuring Bonding Devices
 ==============================

drivers/net/bonding/bond_main.c

···
 static char *fail_over_mac;
 static int all_slaves_active = 0;
 static struct bond_params bonding_defaults;
+static int resend_igmp = BOND_DEFAULT_RESEND_IGMP;
 
 module_param(max_bonds, int, 0);
 MODULE_PARM_DESC(max_bonds, "Max number of bonded devices");
···
 MODULE_PARM_DESC(all_slaves_active, "Keep all frames received on an interface"
 				     "by setting active flag for all slaves.  "
 				     "0 for never (default), 1 for always.");
+module_param(resend_igmp, int, 0);
+MODULE_PARM_DESC(resend_igmp, "Number of IGMP membership reports to send on link failure");
 
 /*----------------------------- Global variables ----------------------------*/
 
···
 		}
 	}
 
+	if (--bond->igmp_retrans > 0)
+		queue_delayed_work(bond->wq, &bond->mcast_work, HZ/5);
+
 	read_unlock(&bond->lock);
 }
 
···
 	 * all were sent on curr_active_slave */
 	if ((USES_PRIMARY(bond->params.mode) && new_active) ||
 	    bond->params.mode == BOND_MODE_ROUNDROBIN) {
+		bond->igmp_retrans = bond->params.resend_igmp;
 		queue_delayed_work(bond->wq, &bond->mcast_work, 0);
 	}
 }
···
 		all_slaves_active = 0;
 	}
 
+	if (resend_igmp < 0 || resend_igmp > 255) {
+		pr_warning("Warning: resend_igmp (%d) should be between "
+			   "0 and 255, resetting to %d\n",
+			   resend_igmp, BOND_DEFAULT_RESEND_IGMP);
+		resend_igmp = BOND_DEFAULT_RESEND_IGMP;
+	}
+
 	/* reset values for TLB/ALB */
 	if ((bond_mode == BOND_MODE_TLB) ||
 	    (bond_mode == BOND_MODE_ALB)) {
···
 	params->fail_over_mac = fail_over_mac_value;
 	params->tx_queues = tx_queues;
 	params->all_slaves_active = all_slaves_active;
+	params->resend_igmp = resend_igmp;
 
 	if (primary) {
 		strncpy(params->primary, primary, IFNAMSIZ);

drivers/net/bonding/bond_sysfs.c

···
 static DEVICE_ATTR(all_slaves_active, S_IRUGO | S_IWUSR,
 		   bonding_show_slaves_active, bonding_store_slaves_active);
 
+/*
+ * Show and set the number of IGMP membership reports to send on link failure
+ */
+static ssize_t bonding_show_resend_igmp(struct device *d,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	struct bonding *bond = to_bond(d);
+
+	return sprintf(buf, "%d\n", bond->params.resend_igmp);
+}
+
+static ssize_t bonding_store_resend_igmp(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) {
+		pr_err("%s: no resend_igmp value specified.\n",
+		       bond->dev->name);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (new_value < 0) {
+		pr_err("%s: Invalid resend_igmp value %d not in range 0-255; rejected.\n",
+		       bond->dev->name, new_value);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	pr_info("%s: Setting resend_igmp to %d.\n",
+		bond->dev->name, new_value);
+	bond->params.resend_igmp = new_value;
+out:
+	return ret;
+}
+
+static DEVICE_ATTR(resend_igmp, S_IRUGO | S_IWUSR,
+		   bonding_show_resend_igmp, bonding_store_resend_igmp);
+
 static struct attribute *per_bond_attrs[] = {
 	&dev_attr_slaves.attr,
 	&dev_attr_mode.attr,
···
 	&dev_attr_ad_partner_mac.attr,
 	&dev_attr_queue_id.attr,
 	&dev_attr_all_slaves_active.attr,
+	&dev_attr_resend_igmp.attr,
 	NULL,
 };
 

drivers/net/bonding/bonding.h

···
 	__be32 arp_targets[BOND_MAX_ARP_TARGETS];
 	int tx_queues;
 	int all_slaves_active;
+	int resend_igmp;
 };
 
 struct bond_parm_tbl {
···
 	s8	 send_grat_arp;
 	s8	 send_unsol_na;
 	s8	 setup_by_slave;
+	s8       igmp_retrans;
 #ifdef CONFIG_PROC_FS
 	struct   proc_dir_entry *proc_entry;
 	char     proc_file_name[IFNAMSIZ];

include/linux/if_bonding.h

···
 #define BOND_DEFAULT_MAX_BONDS  1   /* Default maximum number of devices to support */
 
 #define BOND_DEFAULT_TX_QUEUES 16   /* Default number of tx queues per device */
+
+#define BOND_DEFAULT_RESEND_IGMP	1 /* Default number of IGMP membership reports */
+
 /* hashing types */
 #define BOND_XMIT_POLICY_LAYER2		0 /* layer 2 (MAC only), default */
 #define BOND_XMIT_POLICY_LAYER34	1 /* layer 3+4 (IP ^ (TCP || UDP)) */