| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Mon, 27 Jan 2014 14:36:11 +0100
From: Veaceslav Falico <vfalico@...hat.com>
To: netdev@...r.kernel.org
Cc: Jay Vosburgh <fubar@...ibm.com>,
Andy Gospodarek <andy@...yhouse.net>
Subject: Re: [PATCH v3 net-next 2/2] bonding: restructure locking of
bond_ab_arp_probe()
On Mon, Jan 27, 2014 at 02:33:33PM +0100, Veaceslav Falico wrote:
>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 <fubar@...ibm.com>
>CC: Andy Gospodarek <andy@...yhouse.net>
>Signed-off-by: Veaceslav Falico <vfalico@...hat.com>
>---
>
>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();
Right, git commit --amend would be great after git add...
Sorry, forgot to actually commit changes, will re-send.
>+ /* 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
>
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists