Subject: Re: [RFC PATCH net-next] bonding: Use notifiers for slave link state detection

From: zhuyj <[email-masked]>
Date: Mon, 11 Jan 2016 17:03:43 +0800

Hi, Jay && Emil

I delved into the source code. This patch is based on notifiers. When a 
NETDEV_UP
notifier is received in bond_slave_netdev_event, in 
bond_miimon_inspect_slave, bond_check_dev_link
is called to detect link_state.

Because of link flap, link_state is sometimes different from NETDEV_UP. 
That is, though event is NETDEV_UP,
sometime link_state is down because of link flap.

In the following patch, if link_state is different from the event, it is 
unnecessary to make further setup.

diff --git a/drivers/net/bonding/bond_main.c 
b/drivers/net/bonding/bond_main.c
index 12dd533..1b53da0 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -2012,7 +2012,8 @@ static int bond_slave_info_query(struct net_device 
*bond_dev, struct ifslave *in
  /*-------------------------------- Monitoring 
-------------------------------*/

  /* called with rcu_read_lock() */
-static int bond_miimon_inspect_slave(struct bonding *bond, struct slave 
*slave)
+static int bond_miimon_inspect_slave(struct bonding *bond, struct slave 
*slave,
+                                    unsigned long event)
  {
         int link_state;
         bool ignore_updelay;
@@ -2022,6 +2023,17 @@ static int bond_miimon_inspect_slave(struct 
bonding *bond, struct slave *slave)
         slave->new_link = BOND_LINK_NOCHANGE;

         link_state = bond_check_dev_link(bond, slave->dev, 0);
+       switch (event) {
+       case NETDEV_UP:
+               if (!link_state)
+                       return 0;
+               break;
+
+       case NETDEV_DOWN:
+               if (link_state)
+                       return 0;
+               break;
+       }

         switch (slave->link) {
         case BOND_LINK_UP:
@@ -2107,7 +2119,7 @@ static int bond_miimon_inspect(struct bonding *bond)
         int commit = 0;

         bond_for_each_slave_rcu(bond, slave, iter)
-               commit += bond_miimon_inspect_slave(bond, slave);
+               commit += bond_miimon_inspect_slave(bond, slave, 0xFF);

         return commit;
  }
@@ -3019,7 +3031,7 @@ static int bond_slave_netdev_event(unsigned long 
event,
bond_3ad_adapter_speed_duplex_changed(slave);
                 /* Fallthrough */
         case NETDEV_DOWN:
-               if (bond_miimon_inspect_slave(bond, slave))
+               if (bond_miimon_inspect_slave(bond, slave, event))
                         bond_miimon_commit_slave(bond, slave);

                 /* Refresh slave-array if applicable!

Best Regards!
Zhu Yanjun

On 01/09/2016 10:19 AM, Jay Vosburgh wrote:
> Tantilov, Emil S <[email-masked]> wrote:
>
>>> -----Original Message-----
>> From: Jay Vosburgh [mailto:[email-masked]]
>>> Sent: Thursday, January 07, 2016 5:29 PM
>>> Subject: [RFC PATCH net-next] bonding: Use notifiers for slave link state
>>> detection
>>>
>>>
>>> 	TEST PATCH
>>>
>>> 	This patch modifies bonding to utilize notifier callbacks to
>>> detect slave link state changes.  It is intended to be used with miimon
>>> set to zero, and does not support the updelay or downdelay options to
>>> bonding.  It's not as complicated as it looks; most of the change set is
>>> to break out the inner loop of bond_miimon_inspect into its own
>>> function.
>> Jay,
>>
>> I managed to do a quick test with this patch and occasionally there is
>> a case where I see the bonding driver reporting link up for an
>> interface (eth1) that is not up just yet:
> [...]
>> [12985.213752] ixgbe 0000:01:00.0 eth0: NIC Link is Up 10 Gbps, Flow Control: RX/TX
>> [12985.213970] bond0: link status definitely up for interface eth0, 10000 Mbps full duplex
>> [12985.213975] bond0: link status definitely up for interface eth1, 0 Mbps full duplex
> 	Thanks for testing; the misbehavior is because I cheaped out and
> didn't break out the commit function into a "single slave" version.  The
> below patch (against net-next, replacing the original patch) shouldn't
> generate the erroneous additional link messages any more.
>
> 	This does generate an RCU warning, although the code actually is
> safe (since the notifier callback holds RTNL); I'll sort that out next
> week.
>
> 	-J
>
>
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index cab99fd..12dd533 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -2012,203 +2012,206 @@ static int bond_slave_info_query(struct net_device *bond_dev, struct ifslave *in
>   /*-------------------------------- Monitoring -------------------------------*/
>   
>   /* called with rcu_read_lock() */
> -static int bond_miimon_inspect(struct bonding *bond)
> +static int bond_miimon_inspect_slave(struct bonding *bond, struct slave *slave)
>   {
> -	int link_state, commit = 0;
> -	struct list_head *iter;
> -	struct slave *slave;
> +	int link_state;
>   	bool ignore_updelay;
>   
>   	ignore_updelay = !rcu_dereference(bond->curr_active_slave);
>   
> -	bond_for_each_slave_rcu(bond, slave, iter) {
> -		slave->new_link = BOND_LINK_NOCHANGE;
> +	slave->new_link = BOND_LINK_NOCHANGE;
>   
> -		link_state = bond_check_dev_link(bond, slave->dev, 0);
> +	link_state = bond_check_dev_link(bond, slave->dev, 0);
>   
> -		switch (slave->link) {
> -		case BOND_LINK_UP:
> -			if (link_state)
> -				continue;
> +	switch (slave->link) {
> +	case BOND_LINK_UP:
> +		if (link_state)
> +			return 0;
>   
> -			bond_set_slave_link_state(slave, BOND_LINK_FAIL,
> +		bond_set_slave_link_state(slave, BOND_LINK_FAIL,
> +					  BOND_SLAVE_NOTIFY_LATER);
> +		slave->delay = bond->params.downdelay;
> +		if (slave->delay) {
> +			netdev_info(bond->dev, "link status down for %sinterface %s, disabling it in %d ms\n",
> +				    (BOND_MODE(bond) == BOND_MODE_ACTIVEBACKUP) ?
> +				    (bond_is_active_slave(slave) ?
> +				     "active " : "backup ") : "",
> +				    slave->dev->name,
> +				    bond->params.downdelay * bond->params.miimon);
> +		}
> +		/*FALLTHRU*/
> +	case BOND_LINK_FAIL:
> +		if (link_state) {
> +			/* recovered before downdelay expired */
> +			bond_set_slave_link_state(slave, BOND_LINK_UP,
>   						  BOND_SLAVE_NOTIFY_LATER);
> -			slave->delay = bond->params.downdelay;
> -			if (slave->delay) {
> -				netdev_info(bond->dev, "link status down for %sinterface %s, disabling it in %d ms\n",
> -					    (BOND_MODE(bond) ==
> -					     BOND_MODE_ACTIVEBACKUP) ?
> -					     (bond_is_active_slave(slave) ?
> -					      "active " : "backup ") : "",
> -					    slave->dev->name,
> -					    bond->params.downdelay * bond->params.miimon);
> -			}
> -			/*FALLTHRU*/
> -		case BOND_LINK_FAIL:
> -			if (link_state) {
> -				/* recovered before downdelay expired */
> -				bond_set_slave_link_state(slave, BOND_LINK_UP,
> -							  BOND_SLAVE_NOTIFY_LATER);
> -				slave->last_link_up = jiffies;
> -				netdev_info(bond->dev, "link status up again after %d ms for interface %s\n",
> -					    (bond->params.downdelay - slave->delay) *
> -					    bond->params.miimon,
> -					    slave->dev->name);
> -				continue;
> -			}
> +			slave->last_link_up = jiffies;
> +			netdev_info(bond->dev, "link status up again after %d ms for interface %s\n",
> +				    (bond->params.downdelay - slave->delay) *
> +				    bond->params.miimon, slave->dev->name);
> +			return 0;
> +		}
>   
> -			if (slave->delay <= 0) {
> -				slave->new_link = BOND_LINK_DOWN;
> -				commit++;
> -				continue;
> -			}
> +		if (slave->delay <= 0) {
> +			slave->new_link = BOND_LINK_DOWN;
> +			return 1;
> +		}
>   
> -			slave->delay--;
> -			break;
> +		slave->delay--;
> +		break;
>   
> -		case BOND_LINK_DOWN:
> -			if (!link_state)
> -				continue;
> +	case BOND_LINK_DOWN:
> +		if (!link_state)
> +			return 0;
>   
> -			bond_set_slave_link_state(slave, BOND_LINK_BACK,
> -						  BOND_SLAVE_NOTIFY_LATER);
> -			slave->delay = bond->params.updelay;
> -
> -			if (slave->delay) {
> -				netdev_info(bond->dev, "link status up for interface %s, enabling it in %d ms\n",
> -					    slave->dev->name,
> -					    ignore_updelay ? 0 :
> -					    bond->params.updelay *
> -					    bond->params.miimon);
> -			}
> -			/*FALLTHRU*/
> -		case BOND_LINK_BACK:
> -			if (!link_state) {
> -				bond_set_slave_link_state(slave,
> -							  BOND_LINK_DOWN,
> -							  BOND_SLAVE_NOTIFY_LATER);
> -				netdev_info(bond->dev, "link status down again after %d ms for interface %s\n",
> -					    (bond->params.updelay - slave->delay) *
> -					    bond->params.miimon,
> -					    slave->dev->name);
> +		bond_set_slave_link_state(slave, BOND_LINK_BACK,
> +					  BOND_SLAVE_NOTIFY_LATER);
> +		slave->delay = bond->params.updelay;
>   
> -				continue;
> -			}
> +		if (slave->delay) {
> +			netdev_info(bond->dev, "link status up for interface %s, enabling it in %d ms\n",
> +				    slave->dev->name, ignore_updelay ? 0 :
> +				    bond->params.updelay * bond->params.miimon);
> +		}
> +		/*FALLTHRU*/
> +	case BOND_LINK_BACK:
> +		if (!link_state) {
> +			bond_set_slave_link_state(slave, BOND_LINK_DOWN,
> +						  BOND_SLAVE_NOTIFY_LATER);
> +			netdev_info(bond->dev, "link status down again after %d ms for interface %s\n",
> +				    (bond->params.updelay - slave->delay) *
> +				    bond->params.miimon, slave->dev->name);
>   
> -			if (ignore_updelay)
> -				slave->delay = 0;
> +			return 0;
> +		}
>   
> -			if (slave->delay <= 0) {
> -				slave->new_link = BOND_LINK_UP;
> -				commit++;
> -				ignore_updelay = false;
> -				continue;
> -			}
> +		if (ignore_updelay)
> +			slave->delay = 0;
>   
> -			slave->delay--;
> -			break;
> +		if (slave->delay <= 0) {
> +			slave->new_link = BOND_LINK_UP;
> +			return 1;
>   		}
> +
> +		slave->delay--;
> +		break;
>   	}
>   
> -	return commit;
> +	return 0;
>   }
>   
> -static void bond_miimon_commit(struct bonding *bond)
> +static int bond_miimon_inspect(struct bonding *bond)
>   {
>   	struct list_head *iter;
> -	struct slave *slave, *primary;
> +	struct slave *slave;
> +	int commit = 0;
>   
> -	bond_for_each_slave(bond, slave, iter) {
> -		switch (slave->new_link) {
> -		case BOND_LINK_NOCHANGE:
> -			continue;
> +	bond_for_each_slave_rcu(bond, slave, iter)
> +		commit += bond_miimon_inspect_slave(bond, slave);
>   
> -		case BOND_LINK_UP:
> -			bond_set_slave_link_state(slave, BOND_LINK_UP,
> -						  BOND_SLAVE_NOTIFY_NOW);
> -			slave->last_link_up = jiffies;
> +	return commit;
> +}
>   
> -			primary = rtnl_dereference(bond->primary_slave);
> -			if (BOND_MODE(bond) == BOND_MODE_8023AD) {
> -				/* prevent it from being the active one */
> -				bond_set_backup_slave(slave);
> -			} else if (BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) {
> -				/* make it immediately active */
> -				bond_set_active_slave(slave);
> -			} else if (slave != primary) {
> -				/* prevent it from being the active one */
> -				bond_set_backup_slave(slave);
> -			}
> +static void bond_miimon_commit_slave(struct bonding *bond, struct slave *slave)
> +{
> +	struct slave *primary;
>   
> -			netdev_info(bond->dev, "link status definitely up for interface %s, %u Mbps %s duplex\n",
> -				    slave->dev->name,
> -				    slave->speed == SPEED_UNKNOWN ? 0 : slave->speed,
> -				    slave->duplex ? "full" : "half");
> +	switch (slave->new_link) {
> +	case BOND_LINK_NOCHANGE:
> +		return;
>   
> -			/* notify ad that the link status has changed */
> -			if (BOND_MODE(bond) == BOND_MODE_8023AD)
> -				bond_3ad_handle_link_change(slave, BOND_LINK_UP);
> +	case BOND_LINK_UP:
> +		bond_set_slave_link_state(slave, BOND_LINK_UP,
> +					  BOND_SLAVE_NOTIFY_NOW);
> +		slave->last_link_up = jiffies;
>   
> -			if (bond_is_lb(bond))
> -				bond_alb_handle_link_change(bond, slave,
> -							    BOND_LINK_UP);
> +		primary = rtnl_dereference(bond->primary_slave);
> +		if (BOND_MODE(bond) == BOND_MODE_8023AD) {
> +			/* prevent it from being the active one */
> +			bond_set_backup_slave(slave);
> +		} else if (BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) {
> +			/* make it immediately active */
> +			bond_set_active_slave(slave);
> +		} else if (slave != primary) {
> +			/* prevent it from being the active one */
> +			bond_set_backup_slave(slave);
> +		}
>   
> -			if (BOND_MODE(bond) == BOND_MODE_XOR)
> -				bond_update_slave_arr(bond, NULL);
> +		netdev_info(bond->dev, "link status definitely up for interface %s, %u Mbps %s duplex\n",
> +			    slave->dev->name,
> +			    slave->speed == SPEED_UNKNOWN ? 0 : slave->speed,
> +			    slave->duplex ? "full" : "half");
>   
> -			if (!bond->curr_active_slave || slave == primary)
> -				goto do_failover;
> +		/* notify ad that the link status has changed */
> +		if (BOND_MODE(bond) == BOND_MODE_8023AD)
> +			bond_3ad_handle_link_change(slave, BOND_LINK_UP);
>   
> -			continue;
> +		if (bond_is_lb(bond))
> +			bond_alb_handle_link_change(bond, slave, BOND_LINK_UP);
>   
> -		case BOND_LINK_DOWN:
> -			if (slave->link_failure_count < UINT_MAX)
> -				slave->link_failure_count++;
> +		if (BOND_MODE(bond) == BOND_MODE_XOR)
> +			bond_update_slave_arr(bond, NULL);
>   
> -			bond_set_slave_link_state(slave, BOND_LINK_DOWN,
> -						  BOND_SLAVE_NOTIFY_NOW);
> +		if (!bond->curr_active_slave || slave == primary)
> +			goto do_failover;
>   
> -			if (BOND_MODE(bond) == BOND_MODE_ACTIVEBACKUP ||
> -			    BOND_MODE(bond) == BOND_MODE_8023AD)
> -				bond_set_slave_inactive_flags(slave,
> -							      BOND_SLAVE_NOTIFY_NOW);
> +		goto out;
>   
> -			netdev_info(bond->dev, "link status definitely down for interface %s, disabling it\n",
> -				    slave->dev->name);
> +	case BOND_LINK_DOWN:
> +		if (slave->link_failure_count < UINT_MAX)
> +			slave->link_failure_count++;
>   
> -			if (BOND_MODE(bond) == BOND_MODE_8023AD)
> -				bond_3ad_handle_link_change(slave,
> -							    BOND_LINK_DOWN);
> +		bond_set_slave_link_state(slave, BOND_LINK_DOWN,
> +					  BOND_SLAVE_NOTIFY_NOW);
>   
> -			if (bond_is_lb(bond))
> -				bond_alb_handle_link_change(bond, slave,
> -							    BOND_LINK_DOWN);
> +		if (BOND_MODE(bond) == BOND_MODE_ACTIVEBACKUP ||
> +		    BOND_MODE(bond) == BOND_MODE_8023AD)
> +			bond_set_slave_inactive_flags(slave,
> +						      BOND_SLAVE_NOTIFY_NOW);
>   
> -			if (BOND_MODE(bond) == BOND_MODE_XOR)
> -				bond_update_slave_arr(bond, NULL);
> +		netdev_info(bond->dev, "link status definitely down for interface %s, disabling it\n",
> +			    slave->dev->name);
>   
> -			if (slave == rcu_access_pointer(bond->curr_active_slave))
> -				goto do_failover;
> +		if (BOND_MODE(bond) == BOND_MODE_8023AD)
> +			bond_3ad_handle_link_change(slave, BOND_LINK_DOWN);
>   
> -			continue;
> +		if (bond_is_lb(bond))
> +			bond_alb_handle_link_change(bond, slave, BOND_LINK_DOWN);
>   
> -		default:
> -			netdev_err(bond->dev, "invalid new link %d on slave %s\n",
> -				   slave->new_link, slave->dev->name);
> -			slave->new_link = BOND_LINK_NOCHANGE;
> +		if (BOND_MODE(bond) == BOND_MODE_XOR)
> +			bond_update_slave_arr(bond, NULL);
>   
> -			continue;
> -		}
> +		if (slave == rcu_access_pointer(bond->curr_active_slave))
> +			goto do_failover;
>   
> -do_failover:
> -		block_netpoll_tx();
> -		bond_select_active_slave(bond);
> -		unblock_netpoll_tx();
> +		goto out;
> +
> +	default:
> +		netdev_err(bond->dev, "invalid new link %d on slave %s\n",
> +			   slave->new_link, slave->dev->name);
> +		slave->new_link = BOND_LINK_NOCHANGE;
> +
> +		goto out;
>   	}
>   
> +do_failover:
> +	block_netpoll_tx();
> +	bond_select_active_slave(bond);
> +	unblock_netpoll_tx();
> +
> +out:
>   	bond_set_carrier(bond);
>   }
>   
> +static void bond_miimon_commit(struct bonding *bond)
> +{
> +	struct list_head *iter;
> +	struct slave *slave;
> +
> +	bond_for_each_slave(bond, slave, iter)
> +		bond_miimon_commit_slave(bond, slave);
> +}
> +
>   /* bond_mii_monitor
>    *
>    * Really a wrapper that splits the mii monitor into two phases: an
> @@ -3016,6 +3019,9 @@ static int bond_slave_netdev_event(unsigned long event,
>   			bond_3ad_adapter_speed_duplex_changed(slave);
>   		/* Fallthrough */
>   	case NETDEV_DOWN:
> +		if (bond_miimon_inspect_slave(bond, slave))
> +			bond_miimon_commit_slave(bond, slave);
> +
>   		/* Refresh slave-array if applicable!
>   		 * If the setup does not use miimon or arpmon (mode-specific!),
>   		 * then these events will not cause the slave-array to be
>
>
> ---
> 	-Jay Vosburgh, [email-masked]
>