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Date: Wed, 10 Jan 2007 14:33:58 -0500
From: Andy Gospodarek <andy@...yhouse.net>
To: Stephen Hemminger <shemminger@...l.org>,
Jeff Garzik <jeff@...zik.org>
Cc: fubar@...ibm.com, netdev@...r.kernel.org
Subject: Re: [PATCH 1/1] bonding: eliminate RTNL assertion spew
On Tue, Jan 09, 2007 at 03:09:35PM -0800, Stephen Hemminger wrote:
> On Tue, 9 Jan 2007 17:59:01 -0500
> Andy Gospodarek <andy@...yhouse.net> wrote:
>
> >
> > These changes eliminate the messages indicating that the rtnetlink lock
> > isn't held when bonding tries to change the MAC address of an interface.
> > These calls generally come from timer-pops, but also from sysfs events
> > since neither hold the rtnl lock.
> >
> > The spew generally looks something like this:
> >
> > RTNL: assertion failed at net/core/fib_rules.c (391)
> > [<c028d12e>] fib_rules_event+0x3a/0xeb
> > [<c02da576>] notifier_call_chain+0x19/0x29
> > [<c0280ce6>] dev_set_mac_address+0x46/0x4b
> > [<f8a2a686>] alb_set_slave_mac_addr+0x5d/0x88 [bonding]
> > [<f8a2aa7e>] alb_swap_mac_addr+0x88/0x134 [bonding]
> > [<f8a25ed9>] bond_change_active_slave+0x1a1/0x2c5 [bonding]
> > [<f8a262e8>] bond_select_active_slave+0xa8/0xe1 [bonding]
> > [<f8a27ecb>] bond_mii_monitor+0x3af/0x3fd [bonding]
> > [<c0121896>] run_workqueue+0x85/0xc5
> > [<f8a27b1c>] bond_mii_monitor+0x0/0x3fd [bonding]
> > [<c0121d83>] worker_thread+0xe8/0x119
> > [<c0111179>] default_wake_function+0x0/0xc
> > [<c0121c9b>] worker_thread+0x0/0x119
> > [<c0124099>] kthread+0xad/0xd8
> > [<c0123fec>] kthread+0x0/0xd8
> > .....
> >
> > This patch was mostly inspired from parts of some potential bonding
> > updates Jay Vosburgh <fubar@...ibm.com> and I discussed in December, so
> > he deserves most of the credit for the idea.
> >
> > I've tested it on several systems and it works as I expect. Deadlocks
> > between the rtnl and global bond lock are avoided since we drop the
> > global bond lock before taking the rtnl lock.
> >
>
>
> This seems like the ugly way to do it. Couldn't you just change figure out
> how to acquire RTNL first. It wouldn't hurt to acquire it in the monitor
> routine even if you don't need it.
>
> Conditional locking is a bad road to start down.
Stephen and Jeff,
Does this seem like a better alternative? Taking the rtnetlink lock
before the global bond luck should avoid deadlocks since it is done that
way throughout the bonding code. I didn't notice any immediate problems,
but it was by no means and exhaustive stress test.
Thanks,
-andy
Signed-off-by: Andy Gospodarek <andy@...yhouse.net>
---
bond_main.c | 15 +++++++++++++++
bond_sysfs.c | 6 ++++++
2 files changed, 21 insertions(+)
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 6482aed..e324235 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -2024,6 +2024,9 @@ void bond_mii_monitor(struct net_device
int delta_in_ticks;
int i;
+ /* grab rtnl lock before taking bond lock*/
+ rtnl_lock();
+
read_lock(&bond->lock);
delta_in_ticks = (bond->params.miimon * HZ) / 1000;
@@ -2252,6 +2255,8 @@ re_arm:
}
out:
read_unlock(&bond->lock);
+
+ rtnl_unlock();
}
@@ -2557,6 +2562,9 @@ void bond_loadbalance_arp_mon(struct net
int delta_in_ticks;
int i;
+ /* grab rtnl lock before taking bond lock*/
+ rtnl_lock();
+
read_lock(&bond->lock);
delta_in_ticks = (bond->params.arp_interval * HZ) / 1000;
@@ -2663,6 +2671,8 @@ re_arm:
}
out:
read_unlock(&bond->lock);
+
+ rtnl_unlock();
}
/*
@@ -2687,6 +2697,9 @@ void bond_activebackup_arp_mon(struct ne
int delta_in_ticks;
int i;
+ /* grab rtnl lock before taking bond lock*/
+ rtnl_lock();
+
read_lock(&bond->lock);
delta_in_ticks = (bond->params.arp_interval * HZ) / 1000;
@@ -2911,6 +2924,8 @@ re_arm:
}
out:
read_unlock(&bond->lock);
+
+ rtnl_unlock();
}
/*------------------------------ proc/seq_file-------------------------------*/
diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index ced9ed8..d23057a 100644
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -1028,6 +1028,8 @@ static ssize_t bonding_store_primary(str
struct slave *slave;
struct bonding *bond = to_bond(cd);
+ /* grab rtnl lock before taking bond lock*/
+ rtnl_lock();
write_lock_bh(&bond->lock);
if (!USES_PRIMARY(bond->params.mode)) {
printk(KERN_INFO DRV_NAME
@@ -1063,6 +1065,7 @@ static ssize_t bonding_store_primary(str
}
out:
write_unlock_bh(&bond->lock);
+ rtnl_unlock();
return count;
}
static CLASS_DEVICE_ATTR(primary, S_IRUGO | S_IWUSR, bonding_show_primary, bonding_store_primary);
@@ -1134,6 +1137,8 @@ static ssize_t bonding_store_active_slav
struct slave *new_active = NULL;
struct bonding *bond = to_bond(cd);
+ /* grab rtnl lock before taking bond lock*/
+ rtnl_lock();
write_lock_bh(&bond->lock);
if (!USES_PRIMARY(bond->params.mode)) {
printk(KERN_INFO DRV_NAME
@@ -1191,6 +1196,7 @@ static ssize_t bonding_store_active_slav
}
out:
write_unlock_bh(&bond->lock);
+ rtnl_unlock();
return count;
}
-
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