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Date: Wed, 10 Sep 2014 15:20:37 +0200
From: Nikolay Aleksandrov <nikolay@...hat.com>
To: Mahesh Bandewar <maheshb@...gle.com>,
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>,
Eric Dumazet <edumazet@...gle.com>,
Maciej Zenczykowski <maze@...gle.com>
Subject: Re: [PATCH net-next v2 2/2] bonding: Simplify the xmit function for
modes that use xmit_hash
On 10/09/14 02:46, Mahesh Bandewar wrote:
> 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(-)
>
Hello Mahesh,
First a question, if a bond device in XOR mode is up and we enslave a single
slave how would it start transmitting ? Same question, if we are enslaving a
second device then the array will be rebuild with only the first upon NETDEV_UP
(of course all this is in the case miimon is 0).
The NETDEV_UP upon enslave happens before the slave is linked in.
One side note, you can now simplify these patches and drop the checks for
bond->lock since Dave applied my patches.
A few more important problems below.
> 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;
^^^^^^^^^^^^^^^
What happens if slaves is still NULL ? We'll dereference a NULL pointer here.
I'm beginning to think you don't test these submissions at all, I hit the
obvious NULL pointer dereference immediately after trying to enslave a device in
XOR mode with these patches applied.
> + 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;
^^^^^^^^^^^
Same here, if slaves is NULL we'll dereference a NULL ptr.
> + 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);
>
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