From mboxrd@z Thu Jan 1 00:00:00 1970 From: Veaceslav Falico Subject: [PATCH v3 net-next 2/2] bonding: restructure locking of bond_ab_arp_probe() Date: Mon, 27 Jan 2014 14:33:33 +0100 Message-ID: <1390829613-1842-3-git-send-email-vfalico@redhat.com> References: <1390829613-1842-1-git-send-email-vfalico@redhat.com> Cc: Veaceslav Falico , Jay Vosburgh , Andy Gospodarek To: netdev@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:47252 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753500AbaA0Nhy (ORCPT ); Mon, 27 Jan 2014 08:37:54 -0500 In-Reply-To: <1390829613-1842-1-git-send-email-vfalico@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: Currently we're calling it from under RCU context, however we're using some functions that require rtnl to be held. Fix this by restructuring the locking - don't call it under any locks, aquire rcu_read_lock() if we're sending _only_ (i.e. we have the active slave present), and use rtnl locking otherwise - if we need to modify (in)active flags of a slave. CC: Jay Vosburgh CC: Andy Gospodarek Signed-off-by: Veaceslav Falico --- Notes: v2->v3: Use rtnl_trylock(), not to race with queue cancelling. v1->v2: Add two steps - one for sending/rcu, another for modifying/rtnl. drivers/net/bonding/bond_main.c | 38 ++++++++++++++++++++++++-------------- 1 file changed, 24 insertions(+), 14 deletions(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 27e6fdd..7de0256 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -2605,11 +2605,14 @@ do_failover: static void bond_ab_arp_probe(struct bonding *bond) { struct slave *slave, *before = NULL, *new_slave = NULL, - *curr_arp_slave = rcu_dereference(bond->current_arp_slave), - *curr_active_slave = rcu_dereference(bond->curr_active_slave); + *curr_arp_slave, *curr_active_slave; struct list_head *iter; bool found = false; + rcu_read_lock(); + curr_arp_slave = rcu_dereference(bond->current_arp_slave); + curr_active_slave = rcu_dereference(bond->curr_active_slave); + if (curr_arp_slave && curr_active_slave) pr_info("PROBE: c_arp %s && cas %s BAD\n", curr_arp_slave->dev->name, @@ -2617,23 +2620,31 @@ static void bond_ab_arp_probe(struct bonding *bond) if (curr_active_slave) { bond_arp_send_all(bond, curr_active_slave); + rcu_read_unlock(); return; } + rcu_read_unlock(); /* if we don't have a curr_active_slave, search for the next available * backup slave from the current_arp_slave and make it the candidate * for becoming the curr_active_slave */ + rtnl_lock(); + /* curr_arp_slave might have gone away */ + curr_arp_slave = rcu_dereference(bond->current_arp_slave); + if (!curr_arp_slave) { - curr_arp_slave = bond_first_slave_rcu(bond); - if (!curr_arp_slave) + curr_arp_slave = bond_first_slave(bond); + if (!curr_arp_slave) { + rtnl_unlock(); return; + } } bond_set_slave_inactive_flags(curr_arp_slave); - bond_for_each_slave_rcu(bond, slave, iter) { + bond_for_each_slave(bond, slave, iter) { if (!found && !before && IS_UP(slave->dev)) before = slave; @@ -2663,21 +2674,24 @@ static void bond_ab_arp_probe(struct bonding *bond) if (!new_slave && before) new_slave = before; - if (!new_slave) + if (!new_slave) { + rtnl_unlock(); return; + } new_slave->link = BOND_LINK_BACK; bond_set_slave_active_flags(new_slave); bond_arp_send_all(bond, new_slave); new_slave->jiffies = jiffies; rcu_assign_pointer(bond->current_arp_slave, new_slave); + rtnl_unlock(); } static void bond_activebackup_arp_mon(struct work_struct *work) { struct bonding *bond = container_of(work, struct bonding, arp_work.work); - bool should_notify_peers = false; + bool should_notify_peers = false, should_commit = false; int delta_in_ticks; delta_in_ticks = msecs_to_jiffies(bond->params.arp_interval); @@ -2686,12 +2700,11 @@ static void bond_activebackup_arp_mon(struct work_struct *work) goto re_arm; rcu_read_lock(); - should_notify_peers = bond_should_notify_peers(bond); + should_commit = bond_ab_arp_inspect(bond); + rcu_read_unlock(); - if (bond_ab_arp_inspect(bond)) { - rcu_read_unlock(); - + if (should_commit) { /* Race avoidance with bond_close flush of workqueue */ if (!rtnl_trylock()) { delta_in_ticks = 1; @@ -2700,13 +2713,10 @@ static void bond_activebackup_arp_mon(struct work_struct *work) } bond_ab_arp_commit(bond); - rtnl_unlock(); - rcu_read_lock(); } bond_ab_arp_probe(bond); - rcu_read_unlock(); re_arm: if (bond->params.arp_interval) -- 1.8.4