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Date: Thu, 17 Jan 2008 16:25:02 -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 6/7] 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@...ibm.com>
---
drivers/net/bonding/bond_main.c | 19 ++++++++++++++++
drivers/net/bonding/bond_sysfs.c | 43 ++++++++++++++-----------------------
2 files changed, 35 insertions(+), 27 deletions(-)
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 379c5d8..2c6da49 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)
diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index bff4f2b..90a1f31 100644
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -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)
--
1.5.3.4.206.g58ba4-dirty
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