Subject: Re: [PATCH v2 net-next 6/6] bonding: add an option to fail when any of arp_ip_target is inaccessible

From: Veaceslav Falico <[email-masked]>
Date: Thu, 20 Jun 2013 20:16:24 +0200

On Thu, Jun 20, 2013 at 07:28:55PM +0200, Nikolay Aleksandrov wrote:
>On 20/06/13 18:35, 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.
>>
>> 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 <[email-masked]>
>> ---
>>  Documentation/networking/bonding.txt |   17 ++++++
>>  drivers/net/bonding/bond_main.c      |   36 +++++++++++++-
>>  drivers/net/bonding/bond_sysfs.c     |   91 ++++++++++++++++++++++++++++++----
>>  drivers/net/bonding/bonding.h        |   30 ++++++++++-
>>  4 files changed, 160 insertions(+), 14 deletions(-)
>>
>> diff --git a/Documentation/networking/bonding.txt b/Documentation/networking/bonding.txt
>> index adee3b4..d04f1f5 100644
>> --- a/Documentation/networking/bonding.txt
>> +++ b/Documentation/networking/bonding.txt
>> @@ -321,6 +321,23 @@ 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 f51c379..e19ef34 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},
>> @@ -1483,7 +1492,7 @@ 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 &&
>> @@ -1712,6 +1721,8 @@ 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);
>> @@ -2610,16 +2621,20 @@ 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 (!sip || !bond_has_this_ip(bond, tip)) {
>>  		pr_debug("bva: sip %pI4 tip %pI4 not found\n", &sip, &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;
>>  }
>>
>>  static int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond,
>> @@ -4407,6 +4422,7 @@ 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.
>> @@ -4632,6 +4648,21 @@ static int bond_check_params(struct bond_params *params)
>>  	} else
>>  		arp_validate_value = 0;
>>
>> +	if (arp_all_targets && arp_validate_value) {
>> +		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);
>> +			arp_all_targets_value = 0;
>> +		}
>> +	} else {
>> +		if (!arp_validate_value)
>> +			pr_err("arp_all_targets requires arp_validate\n");
>This will print every time we don't have arp_validate_value (w/ or w/o
>arp_all_targets). The check should probably be if (arp_all_targets &&
>!arp_validate_value).

Yep, missed this one.

>> +		arp_all_targets_value = 0;
>> +	}
>> +
>>  	if (miimon) {
>>  		pr_info("MII link monitoring set to %d ms\n", miimon);
>>  	} else if (arp_interval) {
>> @@ -4696,6 +4727,7 @@ 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 ece57f1..7f8f119 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)
>> +{
>> +	struct bonding *bond = to_bond(d);
>> +	int new_value;
>> +
>> +	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
>> @@ -590,10 +633,14 @@ static ssize_t bonding_store_arp_targets(struct device *d,
>>  					 struct device_attribute *attr,
>>  					 const char *buf, size_t count)
>>  {
>> -	__be32 newtarget;
>> -	int i = 0, ret = -EINVAL;
>>  	struct bonding *bond = to_bond(d);
>> -	__be32 *targets;
>> +	struct slave *slave;
>> +	__be32 newtarget, *targets;
>> +	unsigned long *targets_rx;
>> +	int ind, i, j, ret = -EINVAL;
>> +
>> +	if (!rtnl_trylock())
>> +		return restart_syscall();
>Why do we need RTNL here, what can we race with ?

Yep, artifact from testing, before I've added bond->lock locking.

>>
>>  	targets = bond->params.arp_targets;
>>  	newtarget = in_aton(buf + 1);
>> @@ -611,8 +658,8 @@ static ssize_t bonding_store_arp_targets(struct device *d,
>>  			goto out;
>>  		}
>>
>> -		i = bond_get_targets_ip(targets, 0); /* first free slot */
>> -		if (i == -1) {
>> +		ind = bond_get_targets_ip(targets, 0); /* first free slot */
>> +		if (ind == -1) {
>>  			pr_err("%s: ARP target table is full!\n",
>>  			       bond->dev->name);
>>  			goto out;
>> @@ -620,7 +667,13 @@ static ssize_t bonding_store_arp_targets(struct device *d,
>>
>>  		pr_info("%s: adding ARP target %pI4.\n", bond->dev->name,
>>  			 &newtarget);
>> -		targets[i] = newtarget;
>> +		/* not to race with bond_arp_rcv */
>> +		write_lock(&bond->lock);
>I think this should be _bh since we may get preempted and deadlock.

Yep.

>> +		bond_for_each_slave(bond, slave, i)
>> +			slave->target_last_arp_rx[ind] = slave_last_rx(bond,
>> +								       slave);
>Why not simply jiffies ? The oldest one will still be the oldest one :-)

Hrm, thanks for pointing here - it's actually a small bug - we can fail the
slave with slave_last_rx() (the new target can simply have not enough time
for arp round trip, whilst the previous oldest might have already sent it),
even if the target is actually up and accessible.
And yeah, jiffies works for that. Thanks a lot! :)

>> +		targets[ind] = newtarget;
>> +		write_unlock(&bond->lock);
>>  	} else if (buf[0] == '-')	{
>>  		if ((newtarget == 0) || (newtarget == htonl(INADDR_BROADCAST))) {
>>  			pr_err("%s: invalid ARP target %pI4 specified for removal\n",
>> @@ -628,18 +681,34 @@ static ssize_t bonding_store_arp_targets(struct device *d,
>>  			goto out;
>>  		}
>>
>> -		i = bond_get_targets_ip(targets, newtarget);
>> -		if (i == -1) {
>> -			pr_info("%s: unable to remove nonexistent ARP target %pI4.\n",
>> +		ind = bond_get_targets_ip(targets, newtarget);
>> +		if (ind == -1) {
>> +			pr_err("%s: unable to remove nonexistent ARP target %pI4.\n",
>>  				bond->dev->name, &newtarget);
>>  			goto out;
>>  		}
>>
>> +		if (ind == 0 && targets[1] == 0 && bond->params.arp_validate) {
>> +			pr_err("%s: can't remove last arp target if arp_validate is on\n",
>> +				bond->dev->name);
>> +			goto out;
>> +		}
>Can't I turn arp_validate off, then delete the last target and then turn
>it on again ? Are you fixing the 0 first entry with this ?

You can, it's a bug in bonding_store_arp_validate(), which also should be
addressed, but I wouldn't like to address all the bugs in one patch, and
this one is a great candidate for a standalone patch.

>> +
>>  		pr_info("%s: removing ARP target %pI4.\n", bond->dev->name,
>>  			&newtarget);
>> -		for (; (i < BOND_MAX_ARP_TARGETS-1) && targets[i+1]; i++)
>> +
>> +		write_lock(&bond->lock);
>_bh ditto

Yep.

>> +		bond_for_each_slave(bond, slave, i) {
>> +			targets_rx = slave->target_last_arp_rx;
>> +			j = ind;
>> +			for (; (j < BOND_MAX_ARP_TARGETS-1) && targets[j+1]; j++)
>> +				targets_rx[j] = targets_rx[j+1];
>> +			targets_rx[j] = 0;
>> +		}
>> +		for (i = ind; (i < BOND_MAX_ARP_TARGETS-1) && targets[i+1]; i++)
>>  			targets[i] = targets[i+1];
>>  		targets[i] = 0;
>> +		write_unlock(&bond->lock);
>>  	} else {
>>  		pr_err("no command found in arp_ip_targets file for bond %s. Use +<addr> or -<addr>.\n",
>>  		       bond->dev->name);
>> @@ -649,6 +718,7 @@ static ssize_t bonding_store_arp_targets(struct device *d,
>>
>>  	ret = count;
>>  out:
>> +	rtnl_unlock();
>>  	return ret;
>>  }
>>  static DEVICE_ATTR(arp_ip_target, S_IRUGO | S_IWUSR , bonding_show_arp_targets, bonding_store_arp_targets);
>> @@ -1623,6 +1693,7 @@ 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 486e532..3fb73cc 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[];
>