Message-Id: <1410309999-10596-1-git-send-email-maheshb@google.com>
Date:	Tue,  9 Sep 2014 17:46:39 -0700
From:	Mahesh Bandewar <maheshb@...gle.com>
To:	Jay Vosburgh <j.vosburgh@...il.com>,
	Veaceslav Falico <vfalico@...hat.com>,
	Andy Gospodarek <andy@...yhouse.net>,
	David Miller <davem@...emloft.net>
Cc:	netdev <netdev@...r.kernel.org>,
	Mahesh Bandewar <maheshb@...gle.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Maciej Zenczykowski <maze@...gle.com>
Subject: [PATCH net-next v2 2/2] bonding: Simplify the xmit function for modes that use xmit_hash

Earlier change to use usable slave array for TLB mode had an additional
performance advantage. So extending the same logic to all other modes
that use xmit-hash for slave selection (viz 802.3AD, and XOR modes).
Also consolidating this with the earlier TLB change.

The main idea is to build the usable slaves array in the control path
and use that array for slave selection during xmit operation.

Measured performance in a setup with a bond of 4x1G NICs with 200
instances of netperf for the modes involved (3ad, xor, tlb)
cmd: netperf -t TCP_RR -H <TargetHost> -l 60 -s 5

Mode        TPS-Before   TPS-After

802.3ad   : 468,694      493,101
TLB (lb=0): 392,583      392,965
XOR       : 475,696      484,517

Signed-off-by: Mahesh Bandewar <maheshb@...gle.com>
---
v1:
  (a) If bond_update_slave_arr() fails to allocate memory, it will overwrite
      the slave that need to be removed.
  (b) Freeing of array will assign NULL (to handle bond->down to bond->up
      transition gracefully.
  (c) Change from pr_debug() to pr_err() if bond_update_slave_arr() returns
      failure.
  (d) XOR: bond_update_slave_arr() will consider mii-mon, arp-mon cases and
      will populate the array even if these parameters are not used.
  (e) 3AD: Should handle the ad_agg_selection_logic correctly.
v2:
  (a) Removed rcu_read_{un}lock() calls from array manipulation code.
  (b) Slave link-events now refresh array for all these modes.
  (c) Moved free-array call from bond_close() to bond_uninit().

 drivers/net/bonding/bond_3ad.c  |  76 +++----------------
 drivers/net/bonding/bond_alb.c  |  51 ++-----------
 drivers/net/bonding/bond_alb.h  |   8 --
 drivers/net/bonding/bond_main.c | 158 +++++++++++++++++++++++++++++++++++++---
 drivers/net/bonding/bonding.h   |   8 ++
 5 files changed, 170 insertions(+), 131 deletions(-)

diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index ee2c73a9de39..1549e718074a 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -1579,6 +1579,8 @@ static void ad_agg_selection_logic(struct aggregator *agg)
 				__disable_port(port);
 			}
 		}
+		if (bond_update_slave_arr(bond, NULL))
+			pr_err("Failed to build slave-array for 3ad mode.\n");
 	}
 
 	/* if the selected aggregator is of join individuals
@@ -1717,6 +1719,8 @@ static void ad_enable_collecting_distributing(struct port *port)
 			 port->actor_port_number,
 			 port->aggregator->aggregator_identifier);
 		__enable_port(port);
+		if (bond_update_slave_arr(port->slave->bond, NULL))
+			pr_err("Failed to build slave-array for 3ad mode.\n");
 	}
 }
 
@@ -1733,6 +1737,8 @@ static void ad_disable_collecting_distributing(struct port *port)
 			 port->actor_port_number,
 			 port->aggregator->aggregator_identifier);
 		__disable_port(port);
+		if (bond_update_slave_arr(port->slave->bond, NULL))
+			pr_err("Failed to build slave-array for 3ad mode.\n");
 	}
 }
 
@@ -2311,6 +2317,9 @@ void bond_3ad_handle_link_change(struct slave *slave, char link)
 	 */
 	port->sm_vars |= AD_PORT_BEGIN;
 
+	if (bond_update_slave_arr(slave->bond, NULL))
+		pr_err("Failed to build slave-array for 3ad mode.\n");
+
 	__release_state_machine_lock(port);
 }
 
@@ -2407,73 +2416,6 @@ int bond_3ad_get_active_agg_info(struct bonding *bond, struct ad_info *ad_info)
 	return ret;
 }
 
-int bond_3ad_xmit_xor(struct sk_buff *skb, struct net_device *dev)
-{
-	struct bonding *bond = netdev_priv(dev);
-	struct slave *slave, *first_ok_slave;
-	struct aggregator *agg;
-	struct ad_info ad_info;
-	struct list_head *iter;
-	int slaves_in_agg;
-	int slave_agg_no;
-	int agg_id;
-
-	if (__bond_3ad_get_active_agg_info(bond, &ad_info)) {
-		netdev_dbg(dev, "__bond_3ad_get_active_agg_info failed\n");
-		goto err_free;
-	}
-
-	slaves_in_agg = ad_info.ports;
-	agg_id = ad_info.aggregator_id;
-
-	if (slaves_in_agg == 0) {
-		netdev_dbg(dev, "active aggregator is empty\n");
-		goto err_free;
-	}
-
-	slave_agg_no = bond_xmit_hash(bond, skb) % slaves_in_agg;
-	first_ok_slave = NULL;
-
-	bond_for_each_slave_rcu(bond, slave, iter) {
-		agg = SLAVE_AD_INFO(slave)->port.aggregator;
-		if (!agg || agg->aggregator_identifier != agg_id)
-			continue;
-
-		if (slave_agg_no >= 0) {
-			if (!first_ok_slave && bond_slave_can_tx(slave))
-				first_ok_slave = slave;
-			slave_agg_no--;
-			continue;
-		}
-
-		if (bond_slave_can_tx(slave)) {
-			bond_dev_queue_xmit(bond, skb, slave->dev);
-			goto out;
-		}
-	}
-
-	if (slave_agg_no >= 0) {
-		netdev_err(dev, "Couldn't find a slave to tx on for aggregator ID %d\n",
-			   agg_id);
-		goto err_free;
-	}
-
-	/* we couldn't find any suitable slave after the agg_no, so use the
-	 * first suitable found, if found.
-	 */
-	if (first_ok_slave)
-		bond_dev_queue_xmit(bond, skb, first_ok_slave->dev);
-	else
-		goto err_free;
-
-out:
-	return NETDEV_TX_OK;
-err_free:
-	/* no suitable interface, frame not sent */
-	dev_kfree_skb_any(skb);
-	goto out;
-}
-
 int bond_3ad_lacpdu_recv(const struct sk_buff *skb, struct bonding *bond,
 			 struct slave *slave)
 {
diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
index 73c21e233131..c44cabd8f2ba 100644
--- a/drivers/net/bonding/bond_alb.c
+++ b/drivers/net/bonding/bond_alb.c
@@ -200,7 +200,6 @@ static int tlb_initialize(struct bonding *bond)
 static void tlb_deinitialize(struct bonding *bond)
 {
 	struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond));
-	struct tlb_up_slave *arr;
 
 	_lock_tx_hashtbl_bh(bond);
 
@@ -208,10 +207,6 @@ static void tlb_deinitialize(struct bonding *bond)
 	bond_info->tx_hashtbl = NULL;
 
 	_unlock_tx_hashtbl_bh(bond);
-
-	arr = rtnl_dereference(bond_info->slave_arr);
-	if (arr)
-		kfree_rcu(arr, rcu);
 }
 
 static long long compute_gap(struct slave *slave)
@@ -1409,39 +1404,9 @@ out:
 	return NETDEV_TX_OK;
 }
 
-static int bond_tlb_update_slave_arr(struct bonding *bond,
-				     struct slave *skipslave)
-{
-	struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond));
-	struct slave *tx_slave;
-	struct list_head *iter;
-	struct tlb_up_slave *new_arr, *old_arr;
-
-	new_arr = kzalloc(offsetof(struct tlb_up_slave, arr[bond->slave_cnt]),
-			  GFP_ATOMIC);
-	if (!new_arr)
-		return -ENOMEM;
-
-	bond_for_each_slave(bond, tx_slave, iter) {
-		if (!bond_slave_can_tx(tx_slave))
-			continue;
-		if (skipslave == tx_slave)
-			continue;
-		new_arr->arr[new_arr->count++] = tx_slave;
-	}
-
-	old_arr = rtnl_dereference(bond_info->slave_arr);
-	rcu_assign_pointer(bond_info->slave_arr, new_arr);
-	if (old_arr)
-		kfree_rcu(old_arr, rcu);
-
-	return 0;
-}
-
 int bond_tlb_xmit(struct sk_buff *skb, struct net_device *bond_dev)
 {
 	struct bonding *bond = netdev_priv(bond_dev);
-	struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond));
 	struct ethhdr *eth_data;
 	struct slave *tx_slave = NULL;
 	u32 hash_index;
@@ -1462,12 +1427,14 @@ int bond_tlb_xmit(struct sk_buff *skb, struct net_device *bond_dev)
 							      hash_index & 0xFF,
 							      skb->len);
 			} else {
-				struct tlb_up_slave *slaves;
+				struct bond_up_slave *slaves;
+				unsigned int count;
 
-				slaves = rcu_dereference(bond_info->slave_arr);
-				if (slaves && slaves->count)
+				slaves = rcu_dereference(bond->slave_arr);
+				count = slaves->count;
+				if (slaves && count)
 					tx_slave = slaves->arr[hash_index %
-							       slaves->count];
+							       count];
 			}
 			break;
 		}
@@ -1733,10 +1700,6 @@ void bond_alb_deinit_slave(struct bonding *bond, struct slave *slave)
 		rlb_clear_slave(bond, slave);
 	}
 
-	if (bond_is_nondyn_tlb(bond))
-		if (bond_tlb_update_slave_arr(bond, slave))
-			pr_err("Failed to build slave-array for TLB mode.\n");
-
 }
 
 /* Caller must hold bond lock for read */
@@ -1762,7 +1725,7 @@ void bond_alb_handle_link_change(struct bonding *bond, struct slave *slave, char
 	}
 
 	if (bond_is_nondyn_tlb(bond)) {
-		if (bond_tlb_update_slave_arr(bond, NULL))
+		if (bond_update_slave_arr(bond, NULL))
 			pr_err("Failed to build slave-array for TLB mode.\n");
 	}
 }
diff --git a/drivers/net/bonding/bond_alb.h b/drivers/net/bonding/bond_alb.h
index aaeac61d03cf..5fc76c01636c 100644
--- a/drivers/net/bonding/bond_alb.h
+++ b/drivers/net/bonding/bond_alb.h
@@ -139,20 +139,12 @@ struct tlb_slave_info {
 			 */
 };
 
-struct tlb_up_slave {
-	unsigned int	count;
-	struct rcu_head rcu;
-	struct slave	*arr[0];
-};
-
 struct alb_bond_info {
 	struct tlb_client_info	*tx_hashtbl; /* Dynamically allocated */
 	spinlock_t		tx_hashtbl_lock;
 	u32			unbalanced_load;
 	int			tx_rebalance_counter;
 	int			lp_counter;
-	/* -------- non-dynamic tlb mode only ---------*/
-	struct tlb_up_slave __rcu *slave_arr;	  /* Up slaves */
 	/* -------- rlb parameters -------- */
 	int rlb_enabled;
 	struct rlb_client_info	*rx_hashtbl;	/* Receive hash table */
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index f0f5eab0fab1..456cda67383b 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1693,6 +1693,10 @@ static int __bond_release_one(struct net_device *bond_dev,
 	if (BOND_MODE(bond) == BOND_MODE_8023AD)
 		bond_3ad_unbind_slave(slave);
 
+	if (bond_mode_uses_xmit_hash(bond) &&
+	    bond_update_slave_arr(bond, slave))
+		pr_err("Failed to build slave-array.\n");
+
 	write_unlock_bh(&bond->lock);
 
 	netdev_info(bond_dev, "Releasing %s interface %s\n",
@@ -2009,6 +2013,10 @@ static void bond_miimon_commit(struct bonding *bond)
 				bond_alb_handle_link_change(bond, slave,
 							    BOND_LINK_UP);
 
+			if (BOND_MODE(bond) == BOND_MODE_XOR &&
+			    bond_update_slave_arr(bond, NULL))
+				pr_err("Failed to build slave-array for XOR mode.\n");
+
 			if (!bond->curr_active_slave ||
 			    (slave == bond->primary_slave))
 				goto do_failover;
@@ -2037,6 +2045,10 @@ static void bond_miimon_commit(struct bonding *bond)
 				bond_alb_handle_link_change(bond, slave,
 							    BOND_LINK_DOWN);
 
+			if (BOND_MODE(bond) == BOND_MODE_XOR &&
+			    bond_update_slave_arr(bond, NULL))
+				pr_err("Failed to build slave-array for XOR mode.\n");
+
 			if (slave == rcu_access_pointer(bond->curr_active_slave))
 				goto do_failover;
 
@@ -2500,6 +2512,9 @@ static void bond_loadbalance_arp_mon(struct work_struct *work)
 
 		if (slave_state_changed) {
 			bond_slave_state_change(bond);
+			if (BOND_MODE(bond) == BOND_MODE_XOR &&
+			    bond_update_slave_arr(bond, NULL))
+				pr_err("Failed to build slave-array for XOR mode.\n");
 		} else if (do_failover) {
 			/* the bond_select_active_slave must hold RTNL
 			 * and curr_slave_lock for write.
@@ -2893,11 +2908,23 @@ static int bond_slave_netdev_event(unsigned long event,
 			if (old_duplex != slave->duplex)
 				bond_3ad_adapter_duplex_changed(slave);
 		}
+		/* Refresh slave-array if applicable!
+		 * If the setuo does not use miimon or arpmon (mode-specific!),
+		 * then these event will not cause the slave-array to be
+		 * refreshed. This will cause xmit to use a slave that is not
+		 * usable. Avoid such situation by refeshing the array at these
+		 * events. If these (miimon/arpmon) parameters are configured
+		 * then array gets refreshed twice and that should be fine!
+		 */
+		if (bond_mode_uses_xmit_hash(bond) &&
+		    bond_update_slave_arr(bond, NULL))
+			pr_err("Failed to build slave-array for XOR mode.\n");
 		break;
 	case NETDEV_DOWN:
-		/*
-		 * ... Or is it this?
-		 */
+		/* Refresh slave-array if applicable! */
+		if (bond_mode_uses_xmit_hash(bond) &&
+		    bond_update_slave_arr(bond, NULL))
+			pr_err("Failed to build slave-array for XOR mode.\n");
 		break;
 	case NETDEV_CHANGEMTU:
 		/*
@@ -3143,6 +3170,10 @@ static int bond_open(struct net_device *bond_dev)
 		bond_3ad_initiate_agg_selection(bond, 1);
 	}
 
+	if (bond_mode_uses_xmit_hash(bond) &&
+	    bond_update_slave_arr(bond, NULL))
+		pr_err("Failed to build slave-array for XOR mode.\n");
+
 	return 0;
 }
 
@@ -3684,15 +3715,112 @@ static int bond_xmit_activebackup(struct sk_buff *skb, struct net_device *bond_d
 	return NETDEV_TX_OK;
 }
 
-/* In bond_xmit_xor() , we determine the output device by using a pre-
- * determined xmit_hash_policy(), If the selected device is not enabled,
- * find the next active slave.
+/* Build the usable slaves array in control path for modes that use xmit-hash
+ * to determine the slave interface -
+ * (a) BOND_MODE_8023AD
+ * (b) BOND_MODE_XOR
+ * (c) BOND_MODE_TLB && tlb_dynamic_lb == 0
  */
-static int bond_xmit_xor(struct sk_buff *skb, struct net_device *bond_dev)
+int bond_update_slave_arr(struct bonding *bond, struct slave *skipslave)
 {
-	struct bonding *bond = netdev_priv(bond_dev);
+	struct slave *slave;
+	struct list_head *iter;
+	struct bond_up_slave *new_arr, *old_arr;
+	int slaves_in_agg;
+	int agg_id = 0;
+	int ret = 0;
+
+	if (!bond_has_slaves(bond))
+	    goto out;
+
+	new_arr = kzalloc(offsetof(struct bond_up_slave, arr[bond->slave_cnt]),
+			  GFP_ATOMIC);
+	if (!new_arr) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	if (BOND_MODE(bond) == BOND_MODE_8023AD) {
+		struct ad_info ad_info;
+
+		if (bond_3ad_get_active_agg_info(bond, &ad_info)) {
+			pr_debug("bond_3ad_get_active_agg_info failed\n");
+			kfree_rcu(new_arr, rcu);
+			ret = -EINVAL;
+			goto out;
+		}
+		slaves_in_agg = ad_info.ports;
+		agg_id = ad_info.aggregator_id;
+	}
+	bond_for_each_slave(bond, slave, iter) {
+		if (BOND_MODE(bond) == BOND_MODE_8023AD) {
+			struct aggregator *agg;
+
+			agg = SLAVE_AD_INFO(slave)->port.aggregator;
+			if (!agg || agg->aggregator_identifier != agg_id)
+				continue;
+		}
+		if (!bond_slave_can_tx(slave))
+			continue;
+		if (skipslave == slave)
+			continue;
+		new_arr->arr[new_arr->count++] = slave;
+	}
 
-	bond_xmit_slave_id(bond, skb, bond_xmit_hash(bond, skb) % bond->slave_cnt);
+	old_arr = rcu_dereference_protected(bond->slave_arr,
+					    lockdep_rtnl_is_held() ||
+					    lockdep_is_held(&bond->lock) ||
+					    lockdep_is_held(&bond->curr_slave_lock));
+	rcu_assign_pointer(bond->slave_arr, new_arr);
+	if (old_arr)
+		kfree_rcu(old_arr, rcu);
+
+out:
+	if (ret != 0 && skipslave) {
+		int idx;
+
+		/* Rare situation where caller has asked to skip a specific
+		 * slave but allocation failed (most likely!). BTW this is
+		 * only possible when the call is initiated from
+		 * __bond_release_one(). In this sitation; overwrite the
+		 * skipslave entry in the array with the last entry from the
+		 * array to avoid a situation where the xmit path may choose
+		 * this to-be-skipped slave to send a packet out.
+		 */
+		old_arr = rcu_dereference_protected(bond->slave_arr,
+					    lockdep_is_held(&bond->lock) &&
+					    lockdep_rtnl_is_held());
+		for (idx = 0; idx < old_arr->count; idx++) {
+			if (skipslave == old_arr->arr[idx]) {
+				old_arr->arr[idx] =
+				    old_arr->arr[old_arr->count-1];
+				old_arr->count--;
+				break;
+			}
+		}
+	}
+	return ret;
+}
+
+/* Use this Xmit function for 3AD as well as XOR modes. The current
+ * usable slave array is formed in the control path. The xmit function
+ * just calculates hash and sends the packet out.
+ */
+int bond_3ad_xor_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct bonding *bond = netdev_priv(dev);
+	struct slave *slave;
+	struct bond_up_slave *slaves;
+	unsigned int count;
+
+	slaves = rcu_dereference(bond->slave_arr);
+	count = slaves->count;
+	if (slaves && count) {
+		slave = slaves->arr[bond_xmit_hash(bond, skb) % count];
+		bond_dev_queue_xmit(bond, skb, slave->dev);
+	} else {
+		dev_kfree_skb_any(skb);
+		atomic_long_inc(&dev->tx_dropped);
+	}
 
 	return NETDEV_TX_OK;
 }
@@ -3794,12 +3922,11 @@ static netdev_tx_t __bond_start_xmit(struct sk_buff *skb, struct net_device *dev
 		return bond_xmit_roundrobin(skb, dev);
 	case BOND_MODE_ACTIVEBACKUP:
 		return bond_xmit_activebackup(skb, dev);
+	case BOND_MODE_8023AD:
 	case BOND_MODE_XOR:
-		return bond_xmit_xor(skb, dev);
+		return bond_3ad_xor_xmit(skb, dev);
 	case BOND_MODE_BROADCAST:
 		return bond_xmit_broadcast(skb, dev);
-	case BOND_MODE_8023AD:
-		return bond_3ad_xmit_xor(skb, dev);
 	case BOND_MODE_ALB:
 		return bond_alb_xmit(skb, dev);
 	case BOND_MODE_TLB:
@@ -3980,6 +4107,7 @@ static void bond_uninit(struct net_device *bond_dev)
 	struct bonding *bond = netdev_priv(bond_dev);
 	struct list_head *iter;
 	struct slave *slave;
+	struct bond_up_slave *arr;
 
 	bond_netpoll_cleanup(bond_dev);
 
@@ -3988,6 +4116,12 @@ static void bond_uninit(struct net_device *bond_dev)
 		__bond_release_one(bond_dev, slave->dev, true);
 	netdev_info(bond_dev, "Released all slaves\n");
 
+	arr = rtnl_dereference(bond->slave_arr);
+	if (arr) {
+		kfree_rcu(arr, rcu);
+		RCU_INIT_POINTER(bond->slave_arr, NULL);
+	}
+
 	list_del(&bond->bond_list);
 
 	bond_debug_unregister(bond);
diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index 64b36ba65b89..5642cccd4469 100644
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -177,6 +177,12 @@ struct slave {
 	struct kobject kobj;
 };
 
+struct bond_up_slave {
+	unsigned int	count;
+	struct rcu_head rcu;
+	struct slave	*arr[0];
+};
+
 /*
  * Link pseudo-state only used internally by monitors
  */
@@ -196,6 +202,7 @@ struct bonding {
 	struct   slave __rcu *curr_active_slave;
 	struct   slave __rcu *current_arp_slave;
 	struct   slave *primary_slave;
+	struct   bond_up_slave __rcu *slave_arr; /* Array of usable slaves */
 	bool     force_primary;
 	s32      slave_cnt; /* never change this value outside the attach/detach wrappers */
 	int     (*recv_probe)(const struct sk_buff *, struct bonding *,
@@ -534,6 +541,7 @@ const char *bond_slave_link_status(s8 link);
 struct bond_vlan_tag *bond_verify_device_path(struct net_device *start_dev,
 					      struct net_device *end_dev,
 					      int level);
+int bond_update_slave_arr(struct bonding *bond, struct slave *skipslave);
 
 #ifdef CONFIG_PROC_FS
 void bond_create_proc_entry(struct bonding *bond);
-- 
2.1.0.rc2.206.gedb03e5

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