From: Jay Vosburgh Date: Fri, 18 Jan 2008 00:25:02 +0000 (-0800) Subject: bonding: fix lock ordering for rtnl and bonding_rwsem X-Git-Tag: v2.6.24~41^2~18 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=027ea0416c955778ceca7ef82e48a1dd6b4617c9;p=linux-2.6 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 Signed-off-by: Jeff Garzik --- diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 379c5d87c8..2c6da49693 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 bff4f2b84c..90a1f31e8e 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)