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Message-ID: <20071219144208.GB8728@gospo.usersys.redhat.com>
Date: Wed, 19 Dec 2007 09:42:08 -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 Tue, Dec 18, 2007 at 08:53:39PM +0100, Krzysztof Oledzki wrote:
>
>
> On Fri, 14 Dec 2007, Andy Gospodarek wrote:
>
> >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.
>
> Should I check this patch or rather, based on a future discussion, wait
> for another version?
>
> >
> >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();
> >
>
>
> Best regards,
>
> Krzysztof Olędzki
For now, I prefer Jay's original patch -- with the read_locks (rather
than read/write_lock_bh) and the added rtnl_lock. There is still a
lockdep issue that we need to sort-out, but this patch is needed first.
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