netdev - [PATCH 1/7] bonding: fix locking in sysfs primary/active selection

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Message-Id: <12006159063217-git-send-email-fubar@us.ibm.com>
Date:	Thu, 17 Jan 2008 16:24:57 -0800
From:	Jay Vosburgh <fubar@...ibm.com>
To:	netdev@...r.kernel.org
Cc:	Jeff Garzik <jgarzik@...ox.com>,
	David Miller <davem@...emloft.net>,
	Andy Gospodarek <andy@...yhouse.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jay Vosburgh <fubar@...ibm.com>
Subject: [PATCH 1/7] bonding: fix locking in sysfs primary/active selection

	Fix the functions that store the primary and active slave
options via sysfs to hold the correct locks in the correct order.

	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 (notably for balance-alb mode) 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>
Signed-off-by: Andy Gospodarek <andy@...yhouse.net>
---
 drivers/net/bonding/bond_sysfs.c |   15 ++++++++++-----
 1 files changed, 10 insertions(+), 5 deletions(-)

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;
-- 
1.5.3.4.206.g58ba4-dirty

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