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authorJay Vosburgh <fubar@us.ibm.com>2008-01-17 16:25:02 -0800
committerJeff Garzik <jeff@garzik.org>2008-01-18 14:38:39 -0500
commit027ea0416c955778ceca7ef82e48a1dd6b4617c9 (patch)
treead823fb28b414d948fc372a08c8c15cee31bd8e1 /drivers/net/bonding/bond_main.c
parentece95f7fefe3afae19e641e1b3f5e64b00d5b948 (diff)
bonding: fix lock ordering for rtnl and bonding_rwsem
Fix the handling of rtnl and the bonding_rwsem to always be acquired in a consistent order (rtnl, then bonding_rwsem). The existing code sometimes acquired them in this order, and sometimes in the opposite order, which opens a window for deadlock between ifenslave and sysfs. Signed-off-by: Jay Vosburgh <fubar@us.ibm.com> Signed-off-by: Jeff Garzik <jeff@garzik.org>
Diffstat (limited to 'drivers/net/bonding/bond_main.c')
-rw-r--r--drivers/net/bonding/bond_main.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 379c5d87c80..2c6da496938 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -4874,9 +4874,22 @@ static struct lock_class_key bonding_netdev_xmit_lock_key;
int bond_create(char *name, struct bond_params *params, struct bonding **newbond)
{
struct net_device *bond_dev;
+ struct bonding *bond, *nxt;
int res;
rtnl_lock();
+ down_write(&bonding_rwsem);
+
+ /* Check to see if the bond already exists. */
+ list_for_each_entry_safe(bond, nxt, &bond_dev_list, bond_list)
+ if (strnicmp(bond->dev->name, name, IFNAMSIZ) == 0) {
+ printk(KERN_ERR DRV_NAME
+ ": cannot add bond %s; it already exists\n",
+ name);
+ res = -EPERM;
+ goto out_rtnl;
+ }
+
bond_dev = alloc_netdev(sizeof(struct bonding), name ? name : "",
ether_setup);
if (!bond_dev) {
@@ -4915,10 +4928,12 @@ int bond_create(char *name, struct bond_params *params, struct bonding **newbond
netif_carrier_off(bond_dev);
+ up_write(&bonding_rwsem);
rtnl_unlock(); /* allows sysfs registration of net device */
res = bond_create_sysfs_entry(bond_dev->priv);
if (res < 0) {
rtnl_lock();
+ down_write(&bonding_rwsem);
goto out_bond;
}
@@ -4929,6 +4944,7 @@ out_bond:
out_netdev:
free_netdev(bond_dev);
out_rtnl:
+ up_write(&bonding_rwsem);
rtnl_unlock();
return res;
}
@@ -4949,6 +4965,9 @@ static int __init bonding_init(void)
#ifdef CONFIG_PROC_FS
bond_create_proc_dir();
#endif
+
+ init_rwsem(&bonding_rwsem);
+
for (i = 0; i < max_bonds; i++) {
res = bond_create(NULL, &bonding_defaults, NULL);
if (res)