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Message-ID: <521F59E2.8030707@redhat.com>
Date: Thu, 29 Aug 2013 16:25:38 +0200
From: Nikolay Aleksandrov <nikolay@...hat.com>
To: Ding Tianhong <dingtianhong@...wei.com>
CC: Jay Vosburgh <fubar@...ibm.com>,
Andy Gospodarek <andy@...yhouse.net>,
"David S. Miller" <davem@...emloft.net>,
Veaceslav Falico <vfalico@...hat.com>,
Netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH 1/5] bonding: simplify and use RCU protection for 3ad
xmit path
On 08/28/2013 06:20 AM, Ding Tianhong wrote:
> The commit 278b20837511776dc9d5f6ee1c7fabd5479838bb
> (bonding: initial RCU conversion) has convert the roundrobin, active-backup,
> broadcast and xor xmit path to rcu protection, the performance will be better
> for these mode, so this time, convert xmit path for 3ad mode.
>
> Signed-off-by: Ding Tianhong <dingtianhong@...wei.com>
> Signed-off-by: Wang Yufen <wangyufen@...wei.com>
> Cc: Nikolay Aleksandrov <nikolay@...hat.com>
> Cc: Veaceslav Falico <vfalico@...hat.com>
> ---
> drivers/net/bonding/bond_3ad.c | 31 +++++++++++++------------------
> drivers/net/bonding/bonding.h | 22 ++++++++++++++++++++++
> 2 files changed, 35 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
> index 9010265..52d76a4 100644
> --- a/drivers/net/bonding/bond_3ad.c
> +++ b/drivers/net/bonding/bond_3ad.c
> @@ -143,7 +143,7 @@ static inline struct bonding *__get_bond_by_port(struct port *port)
> */
> static inline struct port *__get_first_port(struct bonding *bond)
> {
> - struct slave *first_slave = bond_first_slave(bond);
> + struct slave *first_slave = bond_first_slave_rcu(bond);
>
> return first_slave ? &(SLAVE_AD_INFO(first_slave).port) : NULL;
> }
> @@ -163,7 +163,7 @@ static inline struct port *__get_next_port(struct port *port)
> // If there's no bond for this port, or this is the last slave
> if (bond == NULL)
> return NULL;
> - slave_next = bond_next_slave(bond, slave);
> + slave_next = bond_next_slave_rcu(bond, slave);
> if (!slave_next || bond_is_first_slave(bond, slave_next))
> return NULL;
>
> @@ -2417,16 +2417,14 @@ int bond_3ad_get_active_agg_info(struct bonding *bond, struct ad_info *ad_info)
>
> int bond_3ad_xmit_xor(struct sk_buff *skb, struct net_device *dev)
> {
> - struct slave *slave, *start_at;
> + struct slave *slave;
Please re-arrange longest -> shortest where possible.
> struct bonding *bond = netdev_priv(dev);
> int slave_agg_no;
> int slaves_in_agg;
> int agg_id;
> - int i;
> struct ad_info ad_info;
> int res = 1;
>
> - read_lock(&bond->lock);
> if (__bond_3ad_get_active_agg_info(bond, &ad_info)) {
> pr_debug("%s: Error: __bond_3ad_get_active_agg_info failed\n",
> dev->name);
> @@ -2444,13 +2442,16 @@ int bond_3ad_xmit_xor(struct sk_buff *skb, struct net_device *dev)
>
> slave_agg_no = bond->xmit_hash_policy(skb, slaves_in_agg);
>
> - bond_for_each_slave(bond, slave) {
> + bond_for_each_slave_rcu(bond, slave) {
> struct aggregator *agg = SLAVE_AD_INFO(slave).port.aggregator;
>
> if (agg && (agg->aggregator_identifier == agg_id)) {
> - slave_agg_no--;
> - if (slave_agg_no < 0)
> - break;
> + if (--slave_agg_no < 0) {
> + if (SLAVE_IS_OK(slave)) {
> + res = bond_dev_queue_xmit(bond, skb, slave->dev);
> + goto out;
> + }
> + }
> }
> }
>
> @@ -2460,23 +2461,17 @@ int bond_3ad_xmit_xor(struct sk_buff *skb, struct net_device *dev)
> goto out;
> }
>
> - start_at = slave;
> -
> - bond_for_each_slave_from(bond, slave, i, start_at) {
> - int slave_agg_id = 0;
> + bond_for_each_slave_rcu(bond, slave) {
> struct aggregator *agg = SLAVE_AD_INFO(slave).port.aggregator;
>
> - if (agg)
> - slave_agg_id = agg->aggregator_identifier;
> -
> - if (SLAVE_IS_OK(slave) && agg && (slave_agg_id == agg_id)) {
> + if (SLAVE_IS_OK(slave) && agg &&
> + (agg->aggregator_identifier == agg_id)) {
Please drop the ( ) from (agg->aggregator_identifier == agg_id), also align it
properly.
> res = bond_dev_queue_xmit(bond, skb, slave->dev);
> break;
> }
> }
>
> out:
> - read_unlock(&bond->lock);
> if (res) {
> /* no suitable interface, frame not sent */
> kfree_skb(skb);
> diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
> index 4bf52d5..ecb5d1d 100644
> --- a/drivers/net/bonding/bonding.h
> +++ b/drivers/net/bonding/bonding.h
> @@ -74,6 +74,9 @@
> /* slave list primitives */
> #define bond_to_slave(ptr) list_entry(ptr, struct slave, list)
>
> +/* slave list primitives, Caller must hold rcu_read_lock */
> +#define bond_to_slave_rcu(ptr) list_entry_rcu(ptr, struct slave, list)
> +
> /* IMPORTANT: bond_first/last_slave can return NULL in case of an empty list */
> #define bond_first_slave(bond) \
> list_first_entry_or_null(&(bond)->slave_list, struct slave, list)
> @@ -81,6 +84,16 @@
> (list_empty(&(bond)->slave_list) ? NULL : \
> bond_to_slave((bond)->slave_list.prev))
>
> +/**
> + * IMPORTANT: bond_first/last_slave_rcu can return NULL in case of an empty list
> + * Caller must hold rcu_read_lock
> + */
Styling nit: the comments in net/ should be /* text...
> +#define bond_first_slave_rcu(bond) \
> + list_first_or_null_rcu(&(bond)->slave_list, struct slave, list)
> +#define bond_last_slave_rcu(bond) \
> + (list_emptry(&(bond)->slave_list) ? NULL : \
^^^^^^^^^^^^^^^^^^^^^
Did you compile this ?
> + bond_to_slave_rcu((bond)->slave_list.prev))
> +
> #define bond_is_first_slave(bond, pos) ((pos)->list.prev == &(bond)->slave_list)
> #define bond_is_last_slave(bond, pos) ((pos)->list.next == &(bond)->slave_list)
>
> @@ -93,6 +106,15 @@
> (bond_is_first_slave(bond, pos) ? bond_last_slave(bond) : \
> bond_to_slave((pos)->list.prev))
>
> +/* Since bond_first/last_slave_rcu can return NULL, these can return NULL too */
> +#define bond_next_slave_rcu(bond, pos) \
> + (bond_is_last_slave(bond, pos) ? bond_first_slave_rcu(bond) : \
> + bond_to_slave_rcu((pos)->list.next))
> +
> +#define bond_prev_slave_rcu(bond, pos) \
> + (bond_is_first_slave(bond, pos) ? bond_last_slave_rcu(bond) : \
> + bond_to_slave_rcu((pos)->list.prev))
> +
> /**
> * bond_for_each_slave_from - iterate the slaves list from a starting point
> * @bond: the bond holding this list.
>
--
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