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Date: Thu, 11 Sep 2014 13:38:38 +0200
From: Nikolay Aleksandrov <nikolay@...hat.com>
To: netdev@...r.kernel.org
Cc: vfalico@...il.com, j.vosburgh@...il.com, andy@...yhouse.net,
davem@...emloft.net, Nikolay Aleksandrov <nikolay@...hat.com>
Subject: [PATCH net-next 2/7] bonding: alb: remove curr_slave_lock
First in rlb_teach_disabled_mac_on_primary() it's okay to remove
curr_slave_lock as all callers except bond_alb_monitor() already hold
RTNL, and in case bond_alb_monitor() is executing we can at most have a
period with bad throughput (very unlikely though).
In bond_alb_monitor() it's okay to remove the read_lock as the slave
list is walked with RCU and the worst that could happen is another
transmitter at the same time and thus for a period which currently is 10
seconds (bond_alb.h: BOND_ALB_LP_TICKS).
And bond_alb_handle_active_change() is okay because it's always called
with RTNL. Removed the ASSERT_RTNL() because it'll be inserted in the
parent function in a following patch.
Signed-off-by: Nikolay Aleksandrov <nikolay@...hat.com>
---
drivers/net/bonding/bond_alb.c | 39 +++------------------------------------
1 file changed, 3 insertions(+), 36 deletions(-)
diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
index 028496205f39..cf4ede8594ff 100644
--- a/drivers/net/bonding/bond_alb.c
+++ b/drivers/net/bonding/bond_alb.c
@@ -447,7 +447,7 @@ static struct slave *__rlb_next_rx_slave(struct bonding *bond)
/* teach the switch the mac of a disabled slave
* on the primary for fault tolerance
*
- * Caller must hold bond->curr_slave_lock for write or bond lock for write
+ * Caller must hold RTNL
*/
static void rlb_teach_disabled_mac_on_primary(struct bonding *bond, u8 addr[])
{
@@ -512,12 +512,8 @@ static void rlb_clear_slave(struct bonding *bond, struct slave *slave)
_unlock_rx_hashtbl_bh(bond);
- write_lock_bh(&bond->curr_slave_lock);
-
if (slave != bond_deref_active_protected(bond))
rlb_teach_disabled_mac_on_primary(bond, slave->dev->dev_addr);
-
- write_unlock_bh(&bond->curr_slave_lock);
}
static void rlb_update_client(struct rlb_client_info *client_info)
@@ -1595,13 +1591,6 @@ void bond_alb_monitor(struct work_struct *work)
if (bond_info->lp_counter >= BOND_ALB_LP_TICKS(bond)) {
bool strict_match;
- /* change of curr_active_slave involves swapping of mac addresses.
- * in order to avoid this swapping from happening while
- * sending the learning packets, the curr_slave_lock must be held for
- * read.
- */
- read_lock(&bond->curr_slave_lock);
-
bond_for_each_slave_rcu(bond, slave, iter) {
/* If updating current_active, use all currently
* user mac addreses (!strict_match). Otherwise, only
@@ -1613,17 +1602,11 @@ void bond_alb_monitor(struct work_struct *work)
alb_send_learning_packets(slave, slave->dev->dev_addr,
strict_match);
}
-
- read_unlock(&bond->curr_slave_lock);
-
bond_info->lp_counter = 0;
}
/* rebalance tx traffic */
if (bond_info->tx_rebalance_counter >= BOND_TLB_REBALANCE_TICKS) {
-
- read_lock(&bond->curr_slave_lock);
-
bond_for_each_slave_rcu(bond, slave, iter) {
tlb_clear_slave(bond, slave, 1);
if (slave == rcu_access_pointer(bond->curr_active_slave)) {
@@ -1633,9 +1616,6 @@ void bond_alb_monitor(struct work_struct *work)
bond_info->unbalanced_load = 0;
}
}
-
- read_unlock(&bond->curr_slave_lock);
-
bond_info->tx_rebalance_counter = 0;
}
@@ -1775,21 +1755,14 @@ void bond_alb_handle_link_change(struct bonding *bond, struct slave *slave, char
* Set the bond->curr_active_slave to @new_slave and handle
* mac address swapping and promiscuity changes as needed.
*
- * If new_slave is NULL, caller must hold curr_slave_lock for write
- *
- * If new_slave is not NULL, caller must hold RTNL, curr_slave_lock
- * for write. Processing here may sleep, so no other locks may be held.
+ * Caller must hold RTNL
*/
void bond_alb_handle_active_change(struct bonding *bond, struct slave *new_slave)
- __releases(&bond->curr_slave_lock)
- __acquires(&bond->curr_slave_lock)
{
struct slave *swap_slave;
struct slave *curr_active;
- curr_active = rcu_dereference_protected(bond->curr_active_slave,
- !new_slave ||
- lockdep_is_held(&bond->curr_slave_lock));
+ curr_active = rtnl_dereference(bond->curr_active_slave);
if (curr_active == new_slave)
return;
@@ -1820,10 +1793,6 @@ void bond_alb_handle_active_change(struct bonding *bond, struct slave *new_slave
tlb_clear_slave(bond, swap_slave, 1);
tlb_clear_slave(bond, new_slave, 1);
- write_unlock_bh(&bond->curr_slave_lock);
-
- ASSERT_RTNL();
-
/* in TLB mode, the slave might flip down/up with the old dev_addr,
* and thus filter bond->dev_addr's packets, so force bond's mac
*/
@@ -1852,8 +1821,6 @@ void bond_alb_handle_active_change(struct bonding *bond, struct slave *new_slave
alb_send_learning_packets(new_slave, bond->dev->dev_addr,
false);
}
-
- write_lock_bh(&bond->curr_slave_lock);
}
/* Called with RTNL */
--
1.9.3
--
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