bonding: Allow userspace to set actors' system_priority in AD system

This patch allows user to randomize the system-priority in an ad-system.
The allowed range is 1 - 0xFFFF while default value is 0xFFFF. If user
does not specify this value, the system defaults to 0xFFFF, which is
what it was before this patch.

Following example code could set the value -
    # modprobe bonding mode=4
    # sys_prio=$(( 1 + RANDOM + RANDOM ))
    # echo $sys_prio > /sys/class/net/bond0/bonding/ad_actor_sys_prio
    # echo +eth1 > /sys/class/net/bond0/bonding/slaves
    ...
    # ip link set bond0 up

Signed-off-by: Mahesh Bandewar <maheshb@google.com>
Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com>
[jt: * fixed up style issues reported by checkpatch
     * changed how the default value is set in bond_check_params(), this
       makes the default consistent between what gets set for a new bond
       and what the default is claimed to be in the bonding options.]
Signed-off-by: Jonathan Toppins <jtoppins@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/bonding.txt

@@ -178,6 +178,15 @@ active_slave
 	active slave, or the empty string if there is no active slave or
 	the current mode does not use an active slave.
 
+ad_actor_sys_prio
+
+	In an AD system, this specifies the system priority. The allowed range
+	is 1 - 65535. If the value is not specified, it takes 65535 as the
+	default value.
+
+	This parameter has effect only in 802.3ad mode and is available through
+	SysFs interface.
+
 ad_select
 
 	Specifies the 802.3ad aggregation selection logic to use.  The

drivers/net/bonding/bond_3ad.c

@@ -1908,7 +1908,8 @@ void bond_3ad_initialize(struct bonding *bond, u16 tick_resolution)
 
 		BOND_AD_INFO(bond).aggregator_identifier = 0;
 
-		BOND_AD_INFO(bond).system.sys_priority = 0xFFFF;
+		BOND_AD_INFO(bond).system.sys_priority =
+			bond->params.ad_actor_sys_prio;
 		BOND_AD_INFO(bond).system.sys_mac_addr = *((struct mac_addr *)bond->dev->dev_addr);
 
 		/* initialize how many times this module is called in one
@@ -1959,6 +1960,8 @@ void bond_3ad_bind_slave(struct slave *slave)
 			port->sm_vars &= ~AD_PORT_LACP_ENABLED;
 		/* actor system is the bond's system */
 		port->actor_system = BOND_AD_INFO(bond).system.sys_mac_addr;
+		port->actor_system_priority =
+		    BOND_AD_INFO(bond).system.sys_priority;
 		/* tx timer(to verify that no more than MAX_TX_IN_SECOND
 		 * lacpdu's are sent in one second)
 		 */

drivers/net/bonding/bond_main.c

@@ -4140,6 +4140,7 @@ static int bond_check_params(struct bond_params *params)
 	struct bond_opt_value newval;
 	const struct bond_opt_value *valptr;
 	int arp_all_targets_value;
+	u16 ad_actor_sys_prio = 0;
 
 	/* Convert string parameters. */
 	if (mode) {
@@ -4434,6 +4435,16 @@ static int bond_check_params(struct bond_params *params)
 		fail_over_mac_value = BOND_FOM_NONE;
 	}
 
+	bond_opt_initstr(&newval, "default");
+	valptr = bond_opt_parse(
+			bond_opt_get(BOND_OPT_AD_ACTOR_SYS_PRIO),
+				     &newval);
+	if (!valptr) {
+		pr_err("Error: No ad_actor_sys_prio default value");
+		return -EINVAL;
+	}
+	ad_actor_sys_prio = valptr->value;
+
 	if (lp_interval == 0) {
 		pr_warn("Warning: ip_interval must be between 1 and %d, so it was reset to %d\n",
 			INT_MAX, BOND_ALB_DEFAULT_LP_INTERVAL);
@@ -4462,6 +4473,7 @@ static int bond_check_params(struct bond_params *params)
 	params->lp_interval = lp_interval;
 	params->packets_per_slave = packets_per_slave;
 	params->tlb_dynamic_lb = 1; /* Default value */
+	params->ad_actor_sys_prio = ad_actor_sys_prio;
 	if (packets_per_slave > 0) {
 		params->reciprocal_packets_per_slave =
 			reciprocal_value(packets_per_slave);

drivers/net/bonding/bond_options.c

@@ -70,6 +70,8 @@ static int bond_option_slaves_set(struct bonding *bond,
 				  const struct bond_opt_value *newval);
 static int bond_option_tlb_dynamic_lb_set(struct bonding *bond,
 				  const struct bond_opt_value *newval);
+static int bond_option_ad_actor_sys_prio_set(struct bonding *bond,
+					     const struct bond_opt_value *newval);
 
 
 static const struct bond_opt_value bond_mode_tbl[] = {
@@ -186,6 +188,12 @@ static const struct bond_opt_value bond_tlb_dynamic_lb_tbl[] = {
 	{ NULL,  -1, 0}
 };
 
+static const struct bond_opt_value bond_ad_actor_sys_prio_tbl[] = {
+	{ "minval",  1,     BOND_VALFLAG_MIN},
+	{ "maxval",  65535, BOND_VALFLAG_MAX | BOND_VALFLAG_DEFAULT},
+	{ NULL,      -1,    0},
+};
+
 static const struct bond_option bond_opts[BOND_OPT_LAST] = {
 	[BOND_OPT_MODE] = {
 		.id = BOND_OPT_MODE,
@@ -379,7 +387,15 @@ static const struct bond_option bond_opts[BOND_OPT_LAST] = {
 		.values = bond_tlb_dynamic_lb_tbl,
 		.flags = BOND_OPTFLAG_IFDOWN,
 		.set = bond_option_tlb_dynamic_lb_set,
-	}
+	},
+	[BOND_OPT_AD_ACTOR_SYS_PRIO] = {
+		.id = BOND_OPT_AD_ACTOR_SYS_PRIO,
+		.name = "ad_actor_sys_prio",
+		.unsuppmodes = BOND_MODE_ALL_EX(BIT(BOND_MODE_8023AD)),
+		.flags = BOND_OPTFLAG_IFDOWN,
+		.values = bond_ad_actor_sys_prio_tbl,
+		.set = bond_option_ad_actor_sys_prio_set,
+	},
 };
 
 /* Searches for an option by name */
@@ -1349,3 +1365,13 @@ static int bond_option_tlb_dynamic_lb_set(struct bonding *bond,
 
 	return 0;
 }
+
+static int bond_option_ad_actor_sys_prio_set(struct bonding *bond,
+					     const struct bond_opt_value *newval)
+{
+	netdev_info(bond->dev, "Setting ad_actor_sys_prio to (%llu)\n",
+		    newval->value);
+
+	bond->params.ad_actor_sys_prio = newval->value;
+	return 0;
+}

drivers/net/bonding/bond_procfs.c

@@ -135,6 +135,8 @@ static void bond_info_show_master(struct seq_file *seq)
 					  bond->params.ad_select);
 		seq_printf(seq, "Aggregator selection policy (ad_select): %s\n",
 			   optval->string);
+		seq_printf(seq, "System priority: %d\n",
+			   BOND_AD_INFO(bond).system.sys_priority);
 
 		if (__bond_3ad_get_active_agg_info(bond, &ad_info)) {
 			seq_printf(seq, "bond %s has no active aggregator\n",

drivers/net/bonding/bond_sysfs.c

@@ -692,6 +692,20 @@ static ssize_t bonding_show_packets_per_slave(struct device *d,
 static DEVICE_ATTR(packets_per_slave, S_IRUGO | S_IWUSR,
 		   bonding_show_packets_per_slave, bonding_sysfs_store_option);
 
+static ssize_t bonding_show_ad_actor_sys_prio(struct device *d,
+					      struct device_attribute *attr,
+					      char *buf)
+{
+	struct bonding *bond = to_bond(d);
+
+	if (BOND_MODE(bond) == BOND_MODE_8023AD)
+		return sprintf(buf, "%hu\n", bond->params.ad_actor_sys_prio);
+
+	return 0;
+}
+static DEVICE_ATTR(ad_actor_sys_prio, S_IRUGO | S_IWUSR,
+		   bonding_show_ad_actor_sys_prio, bonding_sysfs_store_option);
+
 static struct attribute *per_bond_attrs[] = {
 	&dev_attr_slaves.attr,
 	&dev_attr_mode.attr,
@@ -725,6 +739,7 @@ static struct attribute *per_bond_attrs[] = {
 	&dev_attr_lp_interval.attr,
 	&dev_attr_packets_per_slave.attr,
 	&dev_attr_tlb_dynamic_lb.attr,
+	&dev_attr_ad_actor_sys_prio.attr,
 	NULL,
 };
 

include/net/bond_options.h

@@ -63,6 +63,7 @@ enum {
 	BOND_OPT_LP_INTERVAL,
 	BOND_OPT_SLAVES,
 	BOND_OPT_TLB_DYNAMIC_LB,
+	BOND_OPT_AD_ACTOR_SYS_PRIO,
 	BOND_OPT_LAST
 };
 

include/net/bonding.h

@@ -136,6 +136,7 @@ struct bond_params {
 	int packets_per_slave;
 	int tlb_dynamic_lb;
 	struct reciprocal_value reciprocal_packets_per_slave;
+	u16 ad_actor_sys_prio;
 };
 
 struct bond_parm_tbl {