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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>
This commit is contained in:
Jay Vosburgh 2008-01-17 16:25:02 -08:00 committed by Jeff Garzik
parent ece95f7fef
commit 027ea0416c
2 changed files with 35 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
drivers/net/bonding/bond_main.c
View File

@ -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)

43
drivers/net/bonding/bond_sysfs.c
View File

@ -109,11 +109,10 @@ static ssize_t bonding_store_bonds(struct class *cls, const char *buffer, size_t
{
char command[IFNAMSIZ + 1] = {0, };
char *ifname;
int res = count;
int rv, res = count;
struct bonding *bond;
struct bonding *nxt;
down_write(&(bonding_rwsem));
sscanf(buffer, "%16s", command); /* IFNAMSIZ*/
ifname = command + 1;
if ((strlen(command) <= 1) ||
@ -121,39 +120,28 @@ static ssize_t bonding_store_bonds(struct class *cls, const char *buffer, size_t
goto err_no_cmd;
if (command[0] == '+') {
/* 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, ifname, IFNAMSIZ) == 0) {
printk(KERN_ERR DRV_NAME
": cannot add bond %s; it already exists\n",
ifname);
res = -EPERM;
goto out;
}
printk(KERN_INFO DRV_NAME
": %s is being created...\n", ifname);
if (bond_create(ifname, &bonding_defaults, &bond)) {
printk(KERN_INFO DRV_NAME
": %s interface already exists. Bond creation failed.\n",
ifname);
res = -EPERM;
rv = bond_create(ifname, &bonding_defaults, &bond);
if (rv) {
printk(KERN_INFO DRV_NAME ": Bond creation failed.\n");
res = rv;
}
goto out;
}
if (command[0] == '-') {
rtnl_lock();
down_write(&bonding_rwsem);
list_for_each_entry_safe(bond, nxt, &bond_dev_list, bond_list)
if (strnicmp(bond->dev->name, ifname, IFNAMSIZ) == 0) {
rtnl_lock();
/* check the ref count on the bond's kobject.
* If it's > expected, then there's a file open,
* and we have to fail.
*/
if (atomic_read(&bond->dev->dev.kobj.kref.refcount)
> expected_refcount){
rtnl_unlock();
printk(KERN_INFO DRV_NAME
": Unable remove bond %s due to open references.\n",
ifname);
@ -164,6 +152,7 @@ static ssize_t bonding_store_bonds(struct class *cls, const char *buffer, size_t
": %s is being deleted...\n",
bond->dev->name);
bond_destroy(bond);
up_write(&bonding_rwsem);
rtnl_unlock();
goto out;
}
@ -171,6 +160,8 @@ static ssize_t bonding_store_bonds(struct class *cls, const char *buffer, size_t
printk(KERN_ERR DRV_NAME
": unable to delete non-existent bond %s\n", ifname);
res = -ENODEV;
up_write(&bonding_rwsem);
rtnl_unlock();
goto out;
}
@ -183,7 +174,6 @@ err_no_cmd:
* get called forever, which is bad.
*/
out:
up_write(&(bonding_rwsem));
return res;
}
/* class attribute for bond_masters file. This ends up in /sys/class/net */
@ -271,6 +261,9 @@ static ssize_t bonding_store_slaves(struct device *d,
/* Note: We can't hold bond->lock here, as bond_create grabs it. */
rtnl_lock();
down_write(&(bonding_rwsem));
sscanf(buffer, "%16s", command); /* IFNAMSIZ*/
ifname = command + 1;
if ((strlen(command) <= 1) ||
@ -336,12 +329,10 @@ static ssize_t bonding_store_slaves(struct device *d,
dev->mtu = bond->dev->mtu;
}
}
rtnl_lock();
res = bond_enslave(bond->dev, dev);
bond_for_each_slave(bond, slave, i)
if (strnicmp(slave->dev->name, ifname, IFNAMSIZ) == 0)
slave->original_mtu = original_mtu;
rtnl_unlock();
if (res) {
ret = res;
}
@ -359,12 +350,10 @@ static ssize_t bonding_store_slaves(struct device *d,
if (dev) {
printk(KERN_INFO DRV_NAME ": %s: Removing slave %s\n",
bond->dev->name, dev->name);
rtnl_lock();
if (bond->setup_by_slave)
res = bond_release_and_destroy(bond->dev, dev);
else
res = bond_release(bond->dev, dev);
rtnl_unlock();
if (res) {
ret = res;
goto out;
@ -389,6 +378,8 @@ err_no_cmd:
ret = -EPERM;
out:
up_write(&(bonding_rwsem));
rtnl_unlock();
return ret;
}
@ -1423,8 +1414,6 @@ int bond_create_sysfs(void)
int ret = 0;
struct bonding *firstbond;
init_rwsem(&bonding_rwsem);
/* get the netdev class pointer */
firstbond = container_of(bond_dev_list.next, struct bonding, bond_list);
if (!firstbond)