* [PATCH net-next 1/2] bonding: RCUify bond_ab_arp_probe
2014-01-23 11:16 [PATCH net-next 0/2] bonding: fix locking in bond_ab_arp_probe Veaceslav Falico
@ 2014-01-23 11:16 ` Veaceslav Falico
2014-01-23 11:16 ` [PATCH net-next 2/2] bonding: lock RTNL when setting (in)active slave flags Veaceslav Falico
2014-01-23 11:25 ` [PATCH net-next 0/2] bonding: fix locking in bond_ab_arp_probe Veaceslav Falico
2 siblings, 0 replies; 4+ messages in thread
From: Veaceslav Falico @ 2014-01-23 11:16 UTC (permalink / raw)
To: netdev; +Cc: Veaceslav Falico, Jay Vosburgh, Andy Gospodarek
Currently bond_ab_arp_probe() is always called under rcu_read_lock(),
however to work with curr_active_slave we're still holding the
curr_slave_lock.
To remove that curr_slave_lock - rcu_dereference the bond's
curr_active_slave and use it further - so that we're sure the slave won't
go away, and we don't care if it will change in the meanwhile.
CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
---
drivers/net/bonding/bond_main.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index f9e0c8b..22d8b69 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -2605,25 +2605,21 @@ 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_arp_slave = rcu_dereference(bond->current_arp_slave),
+ *curr_active_slave = rcu_dereference(bond->curr_active_slave);
struct list_head *iter;
bool found = false;
- read_lock(&bond->curr_slave_lock);
-
- if (curr_arp_slave && 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,
- bond->curr_active_slave->dev->name);
+ curr_active_slave->dev->name);
- if (bond->curr_active_slave) {
- bond_arp_send_all(bond, bond->curr_active_slave);
- read_unlock(&bond->curr_slave_lock);
+ if (curr_active_slave) {
+ bond_arp_send_all(bond, curr_active_slave);
return;
}
- read_unlock(&bond->curr_slave_lock);
-
/* 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
--
1.8.4
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH net-next 2/2] bonding: lock RTNL when setting (in)active slave flags
2014-01-23 11:16 [PATCH net-next 0/2] bonding: fix locking in bond_ab_arp_probe Veaceslav Falico
2014-01-23 11:16 ` [PATCH net-next 1/2] bonding: RCUify bond_ab_arp_probe Veaceslav Falico
@ 2014-01-23 11:16 ` Veaceslav Falico
2014-01-23 11:25 ` [PATCH net-next 0/2] bonding: fix locking in bond_ab_arp_probe Veaceslav Falico
2 siblings, 0 replies; 4+ messages in thread
From: Veaceslav Falico @ 2014-01-23 11:16 UTC (permalink / raw)
To: netdev; +Cc: Veaceslav Falico, Jay Vosburgh, Andy Gospodarek
Currently, on (in)active slave flag change, we notify the stack via
rtmsg_ifinfo(), which implies that we should hold the RTNL lock.
However, in bond_ab_arp_probe(), in case we don't have curr_active_slave -
we don't hold it, which issues a warning and might race with other slave
flags modifications.
Fix this by wrapping the changing in RTNL lock - it's not a hot path (runs
every arp_interval) - so no speed issues should arrive.
CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
---
drivers/net/bonding/bond_main.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 22d8b69..50cddb9 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -2631,9 +2631,11 @@ static void bond_ab_arp_probe(struct bonding *bond)
return;
}
+ rtnl_lock();
+
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;
@@ -2660,6 +2662,8 @@ static void bond_ab_arp_probe(struct bonding *bond)
found = true;
}
+ rtnl_unlock();
+
if (!new_slave && before)
new_slave = before;
--
1.8.4
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH net-next 0/2] bonding: fix locking in bond_ab_arp_probe
2014-01-23 11:16 [PATCH net-next 0/2] bonding: fix locking in bond_ab_arp_probe Veaceslav Falico
2014-01-23 11:16 ` [PATCH net-next 1/2] bonding: RCUify bond_ab_arp_probe Veaceslav Falico
2014-01-23 11:16 ` [PATCH net-next 2/2] bonding: lock RTNL when setting (in)active slave flags Veaceslav Falico
@ 2014-01-23 11:25 ` Veaceslav Falico
2 siblings, 0 replies; 4+ messages in thread
From: Veaceslav Falico @ 2014-01-23 11:25 UTC (permalink / raw)
To: netdev; +Cc: Jay Vosburgh, Andy Gospodarek
On Thu, Jan 23, 2014 at 12:16:02PM +0100, Veaceslav Falico wrote:
>Hi,
>
>After the latest patches, on every call of bond_ab_arp_probe() without an
>active slave I see the following warning:
Self-NAK, there are still warnings comming out from bond_ab_arp_probe and
from other parts. Calling rtnl-needed functions on that low-level functions
wasn't the best idea...
Will send v2 to fix this warning.
>
>[ 7.912314] RTNL: assertion failed at net/core/dev.c (4494)
>...
>[ 7.922495] [<ffffffff817acc6f>] dump_stack+0x51/0x72
>[ 7.923714] [<ffffffff8168795e>] netdev_master_upper_dev_get+0x6e/0x70
>[ 7.924940] [<ffffffff816a2a66>] rtnl_link_fill+0x116/0x260
>[ 7.926143] [<ffffffff817acc6f>] ? dump_stack+0x51/0x72
>[ 7.927333] [<ffffffff816a350c>] rtnl_fill_ifinfo+0x95c/0xb90
>[ 7.928529] [<ffffffff8167af2b>] ? __kmalloc_reserve+0x3b/0xa0
>[ 7.929681] [<ffffffff8167bfcf>] ? __alloc_skb+0x9f/0x1e0
>[ 7.930827] [<ffffffff816a3b64>] rtmsg_ifinfo+0x84/0x100
>[ 7.931960] [<ffffffffa00bca07>] bond_ab_arp_probe+0x1a7/0x370 [bonding]
>[ 7.933133] [<ffffffffa00bcd78>] bond_activebackup_arp_mon+0x1a8/0x2f0 [bonding]
>...
>
>It happens because in bond_ab_arp_probe() we change the flags of a slave
>without holding the RTNL lock.
>
>To fix this - remove the useless curr_active_lock, RCUify it completely and
>lock RTNL while changing the slave's flags.
>
>CC: Jay Vosburgh <fubar@us.ibm.com>
>CC: Andy Gospodarek <andy@greyhouse.net>
>CC: netdev@vger.kernel.org
>Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
>
>---
> drivers/net/bonding/bond_main.c | 22 +++++++++++-----------
> 1 file changed, 11 insertions(+), 11 deletions(-)
>
^ permalink raw reply [flat|nested] 4+ messages in thread