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Date: Fri, 14 Dec 2007 17:47:22 -0500
From: Andy Gospodarek <andy@...yhouse.net>
To: Krzysztof Oledzki <olel@....pl>
Cc: Andy Gospodarek <andy@...yhouse.net>,
Jay Vosburgh <fubar@...ibm.com>,
Herbert Xu <herbert@...dor.apana.org.au>,
Andrew Morton <akpm@...ux-foundation.org>,
bugme-daemon@...zilla.kernel.org, shemminger@...ux-foundation.org,
davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [Bugme-new] [Bug 9543] New: RTNL: assertion failed at net/ipv6/addrconf.c (2164)/RTNL: assertion failed at net/ipv4/devinet.c (1055)
On Fri, Dec 14, 2007 at 07:57:42PM +0100, Krzysztof Oledzki wrote:
>
>
> On Fri, 14 Dec 2007, Andy Gospodarek wrote:
>
> >On Fri, Dec 14, 2007 at 05:14:57PM +0100, Krzysztof Oledzki wrote:
> >>
> >>
> >>On Wed, 12 Dec 2007, Jay Vosburgh wrote:
> >>
> >>>Herbert Xu <herbert@...dor.apana.org.au> wrote:
> >>>
> >>>>>diff -puN drivers/net/bonding/bond_sysfs.c~bonding-locking-fix
> >>>>>drivers/net/bonding/bond_sysfs.c
> >>>>>--- a/drivers/net/bonding/bond_sysfs.c~bonding-locking-fix
> >>>>>+++ a/drivers/net/bonding/bond_sysfs.c
> >>>>>@@ -1111,8 +1111,6 @@ static ssize_t bonding_store_primary(str
> >>>>>out:
> >>>>> write_unlock_bh(&bond->lock);
> >>>>>
> >>>>>- rtnl_unlock();
> >>>>>-
> >>>>
> >>>>Looking at the changeset that added this perhaps the intention
> >>>>is to hold the lock? If so we should add an rtnl_lock to the start
> >>>>of the function.
> >>>
> >>> Yes, this function needs to hold locks, and more than just
> >>>what's there now. I believe the following should be correct; I haven't
> >>>tested it, though (I'm supposedly on vacation right now).
> >>>
> >>> The following change should be correct for the
> >>>bonding_store_primary case discussed in this thread, and also corrects
> >>>the bonding_store_active case which performs similar functions.
> >>>
> >>> The bond_change_active_slave and bond_select_active_slave
> >>>functions both require rtnl, bond->lock for read and curr_slave_lock for
> >>>write_bh, and no other locks. This is so that the lower level
> >>>mode-specific functions can release locks down to just rtnl in order to
> >>>call, e.g., dev_set_mac_address with the locks it expects (rtnl only).
> >>>
> >>>Signed-off-by: Jay Vosburgh <fubar@...ibm.com>
> >>>
> >>>diff --git a/drivers/net/bonding/bond_sysfs.c
> >>>b/drivers/net/bonding/bond_sysfs.c
> >>>index 11b76b3..28a2d80 100644
> >>>--- a/drivers/net/bonding/bond_sysfs.c
> >>>+++ b/drivers/net/bonding/bond_sysfs.c
> >>>@@ -1075,7 +1075,10 @@ static ssize_t bonding_store_primary(struct device
> >>>*d,
> >>> struct slave *slave;
> >>> struct bonding *bond = to_bond(d);
> >>>
> >>>- write_lock_bh(&bond->lock);
> >>>+ rtnl_lock();
> >>>+ read_lock(&bond->lock);
> >>>+ write_lock_bh(&bond->curr_slave_lock);
> >>>+
> >>> if (!USES_PRIMARY(bond->params.mode)) {
> >>> printk(KERN_INFO DRV_NAME
> >>> ": %s: Unable to set primary slave; %s is in mode
> >>> %d\n",
> >>>@@ -1109,8 +1112,8 @@ static ssize_t bonding_store_primary(struct device
> >>>*d,
> >>> }
> >>> }
> >>>out:
> >>>- write_unlock_bh(&bond->lock);
> >>>-
> >>>+ write_unlock_bh(&bond->curr_slave_lock);
> >>>+ read_unlock(&bond->lock);
> >>> rtnl_unlock();
> >>>
> >>> return count;
> >>>@@ -1190,7 +1193,8 @@ static ssize_t bonding_store_active_slave(struct
> >>>device *d,
> >>> struct bonding *bond = to_bond(d);
> >>>
> >>> rtnl_lock();
> >>>- write_lock_bh(&bond->lock);
> >>>+ read_lock(&bond->lock);
> >>>+ write_lock_bh(&bond->curr_slave_lock);
> >>>
> >>> if (!USES_PRIMARY(bond->params.mode)) {
> >>> printk(KERN_INFO DRV_NAME
> >>>@@ -1247,7 +1251,8 @@ static ssize_t bonding_store_active_slave(struct
> >>>device *d,
> >>> }
> >>> }
> >>>out:
> >>>- write_unlock_bh(&bond->lock);
> >>>+ write_unlock_bh(&bond->curr_slave_lock);
> >>>+ read_unlock(&bond->lock);
> >>> rtnl_unlock();
> >>>
> >>> return count;
> >>
> >>Vanilla 2.6.24-rc5 plus this patch:
> >>
> >>=========================================================
> >>[ INFO: possible irq lock inversion dependency detected ]
> >>2.6.24-rc5 #1
> >>---------------------------------------------------------
> >>events/0/9 just changed the state of lock:
> >> (&mc->mca_lock){-+..}, at: [<c0411c7a>] mld_ifc_timer_expire+0x130/0x1fb
> >>but this lock took another, soft-read-irq-unsafe lock in the past:
> >> (&bond->lock){-.--}
> >>
> >>and interrupts could create inverse lock ordering between them.
> >>
> >>
> >
> >Grrr, I should have seen that -- sorry. Try your luck with this instead:
> <CUT>
>
> No luck.
>
I'm guessing if we go back to using a write-lock for bond->lock this
will go back to working again, but I'm not totally convinced since there
are plenty of places where we used a read-lock with it.
diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index 11b76b3..635b857 100644
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -1075,7 +1075,10 @@ static ssize_t bonding_store_primary(struct device *d,
struct slave *slave;
struct bonding *bond = to_bond(d);
+ rtnl_lock();
write_lock_bh(&bond->lock);
+ write_lock_bh(&bond->curr_slave_lock);
+
if (!USES_PRIMARY(bond->params.mode)) {
printk(KERN_INFO DRV_NAME
": %s: Unable to set primary slave; %s is in mode %d\n",
@@ -1109,8 +1112,8 @@ static ssize_t bonding_store_primary(struct device *d,
}
}
out:
+ write_unlock_bh(&bond->curr_slave_lock);
write_unlock_bh(&bond->lock);
-
rtnl_unlock();
return count;
@@ -1191,6 +1194,7 @@ static ssize_t bonding_store_active_slave(struct device *d,
rtnl_lock();
write_lock_bh(&bond->lock);
+ write_lock_bh(&bond->curr_slave_lock);
if (!USES_PRIMARY(bond->params.mode)) {
printk(KERN_INFO DRV_NAME
@@ -1247,6 +1251,7 @@ static ssize_t bonding_store_active_slave(struct device *d,
}
}
out:
+ write_unlock_bh(&bond->curr_slave_lock);
write_unlock_bh(&bond->lock);
rtnl_unlock();
--
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