netdev - Re: [Bugme-new] [Bug 9543] New: RTNL: assertion failed at net/ipv6/addrconf.c (2164)/RTNL: assertion failed at net/ipv4/devinet.c (1055)

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Date:	Wed, 12 Dec 2007 09:46:55 -0800
From:	Jay Vosburgh <fubar@...ibm.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
cc:	akpm@...ux-foundation.org (Andrew Morton), olel@....pl,
	bugme-daemon@...zilla.kernel.org, shemminger@...ux-foundation.org,
	davem@...emloft.net, netdev@...r.kernel.org, andy@...yhouse.net
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) 

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;

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