Subject: Re: [PATCH net-next 6/6] bonding: add an option to fail when any of arp_ip_target is inaccessible

From: Nikolay Aleksandrov <[email-masked]>
Date: Wed, 19 Jun 2013 23:58:52 +0200

On 19/06/13 19:34, Veaceslav Falico wrote:
> 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.
> 
> Signed-off-by: Veaceslav Falico <[email-masked]>
> ---
>  Documentation/networking/bonding.txt |   17 +++++++++++++
>  drivers/net/bonding/bond_main.c      |   38 +++++++++++++++++++++++++++-
>  drivers/net/bonding/bond_sysfs.c     |   44 ++++++++++++++++++++++++++++++++++
>  drivers/net/bonding/bonding.h        |   30 +++++++++++++++++++++-
>  4 files changed, 125 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/networking/bonding.txt b/Documentation/networking/bonding.txt
> index 84f16c8..284b4ab 100644
> --- a/Documentation/networking/bonding.txt
> +++ b/Documentation/networking/bonding.txt
> @@ -309,6 +309,23 @@ arp_validate
>  
>  	This option was added in bonding version 3.1.0.
>  
> +arp_all_targets
> +
> +	Specifies whether, in active-backup mode with arp validation,
> +	any of the arp_ip_targets should be up to keep the slave up
> +	(default) or it should go down if at least one of
> +	arp_ip_targets doesn't reply to arp requests.
> +
> +	Possible values are:
> +
> +	any or 0
> +
> +		consider the slave up if any of the arp_ip_targets is up
> +
> +	all or 1
> +
> +		consider the slave up if all of the arp_ip_targets are up
> +
>  downdelay
>  
>  	Specifies the time, in milliseconds, to wait before disabling
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 3f64607..6136e5e 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -104,6 +104,7 @@ static char *xmit_hash_policy;
>  static int arp_interval = BOND_LINK_ARP_INTERV;
>  static char *arp_ip_target[BOND_MAX_ARP_TARGETS];
>  static char *arp_validate;
> +static char *arp_all_targets;
>  static char *fail_over_mac;
>  static int all_slaves_active = 0;
>  static struct bond_params bonding_defaults;
> @@ -166,6 +167,8 @@ module_param(arp_validate, charp, 0);
>  MODULE_PARM_DESC(arp_validate, "validate src/dst of ARP probes; "
>  			       "0 for none (default), 1 for active, "
>  			       "2 for backup, 3 for all");
> +module_param(arp_all_targets, charp, 0);
> +MODULE_PARM_DESC(arp_all_targets, "fail on any/all arp targets timeout; 0 for any (default), 1 for all");
>  module_param(fail_over_mac, charp, 0);
>  MODULE_PARM_DESC(fail_over_mac, "For active-backup, do not set all slaves to "
>  				"the same MAC; 0 for none (default), "
> @@ -216,6 +219,12 @@ const struct bond_parm_tbl xmit_hashtype_tbl[] = {
>  {	NULL,			-1},
>  };
>  
> +const struct bond_parm_tbl arp_all_targets_tbl[] = {
> +{	"any",			BOND_ARP_TARGETS_ANY},
> +{	"all",			BOND_ARP_TARGETS_ALL},
> +{	NULL,			-1},
> +};
> +
>  const struct bond_parm_tbl arp_validate_tbl[] = {
>  {	"none",			BOND_ARP_VALIDATE_NONE},
>  {	"active",		BOND_ARP_VALIDATE_ACTIVE},
> @@ -1476,7 +1485,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
>  	struct slave *new_slave = NULL;
>  	struct sockaddr addr;
>  	int link_reporting;
> -	int res = 0;
> +	int res = 0, i;
>  
>  	if (!bond->params.use_carrier &&
>  	    slave_dev->ethtool_ops->get_link == NULL &&
> @@ -1705,6 +1714,8 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
>  
>  	new_slave->last_arp_rx = jiffies -
>  		(msecs_to_jiffies(bond->params.arp_interval) + 1);
> +	for (i = 0; i < BOND_MAX_ARP_TARGETS; i++)
> +		new_slave->target_last_arp_rx[i] = jiffies;
>  
>  	if (bond->params.miimon && !bond->params.use_carrier) {
>  		link_reporting = bond_check_dev_link(bond, slave_dev, 1);
> @@ -2599,17 +2610,21 @@ static void bond_arp_send_all(struct bonding *bond, struct slave *slave)
>  
>  static void bond_validate_arp(struct bonding *bond, struct slave *slave, __be32 sip, __be32 tip)
>  {
> +	int i;
> +
>  	if (!bond_has_this_ip(bond, tip)) {
>  		pr_debug("bva: tip %pI4 not found\n", &tip);
>  		return;
>  	}
>  
> -	if (bond_get_targets_ip(bond->params.arp_targets, sip) == -1) {
> +	i = bond_get_targets_ip(bond->params.arp_targets, sip);
> +	if (i == -1) {
>  		pr_debug("bva: sip %pI4 not found in targets\n", &sip);
>  		return;
>  	}
>  
>  	slave->last_arp_rx = jiffies;
> +	slave->target_last_arp_rx[i] = jiffies;
>  }
Here again it's probably good to check if sip != 0 (0.0.0.0) because you
can alter the jiffies of the first free slot otherwise.
>  
>  static int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond,
> @@ -4381,6 +4396,7 @@ int bond_parse_parm(const char *buf, const struct bond_parm_tbl *tbl)
>  static int bond_check_params(struct bond_params *params)
>  {
>  	int arp_validate_value, fail_over_mac_value, primary_reselect_value, i;
> +	int arp_all_targets_value;
>  
>  	/*
>  	 * Convert string parameters.
> @@ -4606,6 +4622,23 @@ static int bond_check_params(struct bond_params *params)
>  	} else
>  		arp_validate_value = 0;
>  
> +	if (arp_all_targets) {
> +		if (!arp_validate_value) {
> +			pr_err("arp_all_targets requires arp_validate\n");
> +			return -EINVAL;
> +		}
I don't think it's necessary to prevent module from loading. You can
just revert to default value with an error message IMO.
> +
> +		arp_all_targets_value = bond_parse_parm(arp_all_targets,
> +							arp_all_targets_tbl);
> +
> +		if (arp_all_targets_value == -1) {
> +			pr_err("Error: invalid arp_all_targets_value \"%s\"\n",
> +			       arp_all_targets);
> +			return -EINVAL;
> +		}
Again I think you can just default here, no need to prevent module from
loading, an error message would be enough IMO.
> +	} else
> +		arp_all_targets_value = 0;
> +
"else" statement should be in { } since the "if" before is (CodingStyle).
>  	if (miimon) {
>  		pr_info("MII link monitoring set to %d ms\n", miimon);
>  	} else if (arp_interval) {
> @@ -4670,6 +4703,7 @@ static int bond_check_params(struct bond_params *params)
>  	params->num_peer_notif = num_peer_notif;
>  	params->arp_interval = arp_interval;
>  	params->arp_validate = arp_validate_value;
> +	params->arp_all_targets = arp_all_targets_value;
>  	params->updelay = updelay;
>  	params->downdelay = downdelay;
>  	params->use_carrier = use_carrier;
> diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
> index e680151..09fb9f7 100644
> --- a/drivers/net/bonding/bond_sysfs.c
> +++ b/drivers/net/bonding/bond_sysfs.c
> @@ -443,6 +443,49 @@ static ssize_t bonding_store_arp_validate(struct device *d,
>  
>  static DEVICE_ATTR(arp_validate, S_IRUGO | S_IWUSR, bonding_show_arp_validate,
>  		   bonding_store_arp_validate);
> +/*
> + * Show and set arp_all_targets.
> + */
> +static ssize_t bonding_show_arp_all_targets(struct device *d,
> +					 struct device_attribute *attr,
> +					 char *buf)
> +{
> +	struct bonding *bond = to_bond(d);
> +	int value = bond->params.arp_all_targets;
> +
> +	return sprintf(buf, "%s %d\n", arp_all_targets_tbl[value].modename,
> +		       value);
> +}
> +
> +static ssize_t bonding_store_arp_all_targets(struct device *d,
> +					  struct device_attribute *attr,
> +					  const char *buf, size_t count)
> +{
> +	int new_value;
> +	struct bonding *bond = to_bond(d);
I'd say struct first, int second, but that's just a minor nitpick/opinion.
> +
> +	new_value = bond_parse_parm(buf, arp_all_targets_tbl);
> +	if (new_value < 0) {
> +		pr_err("%s: Ignoring invalid arp_all_targets value %s\n",
> +		       bond->dev->name, buf);
> +		return -EINVAL;
> +	}
> +	if (new_value && !bond->params.arp_validate) {
> +		pr_err("%s: arp_all_targets requires arp_validate.\n",
> +		       bond->dev->name);
> +		return -EINVAL;
> +	}
> +	pr_info("%s: setting arp_all_targets to %s (%d).\n",
> +		bond->dev->name, arp_all_targets_tbl[new_value].modename,
> +		new_value);
> +
> +	bond->params.arp_all_targets = new_value;
> +
> +	return count;
> +}
> +
> +static DEVICE_ATTR(arp_all_targets, S_IRUGO | S_IWUSR,
> +		   bonding_show_arp_all_targets, bonding_store_arp_all_targets);
>  
>  /*
>   * Show and store fail_over_mac.  User only allowed to change the
> @@ -1625,6 +1668,7 @@ static struct attribute *per_bond_attrs[] = {
>  	&dev_attr_mode.attr,
>  	&dev_attr_fail_over_mac.attr,
>  	&dev_attr_arp_validate.attr,
> +	&dev_attr_arp_all_targets.attr,
>  	&dev_attr_arp_interval.attr,
>  	&dev_attr_arp_ip_target.attr,
>  	&dev_attr_downdelay.attr,
> diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
> index 7feab6c..29fc8d6 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];
This is the part I resist since struct slave is huge as it is, and this
is just making it bigger. I know it's necessary and all, just saying :-)
>  	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;
I wonder if there's a chance to return 0 from slave_oldest_target_arp_rx
here in the case of no arp IP targets or even in the case of adding an
IP target after the enslaving and prior to receiving an ARP from it,
since there're places where some values can be decremented from that and
we'll end up with 0 - something.
Because in the old case last_arp_rx was set while enslaving.
> +	}
>  
>  	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[];