The patch titled bonding: fix lock ordering for rtnl and bonding_rwsem has been added to the -mm tree. Its filename is bonding-fix-lock-ordering-for-rtnl-and-bonding_rwsem.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: bonding: fix lock ordering for rtnl and bonding_rwsem From: Jay Vosburgh <fubar@xxxxxxxxxx> 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@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/net/bonding/bond_main.c | 19 ++++++++++++ drivers/net/bonding/bond_sysfs.c | 43 ++++++++++------------------- 2 files changed, 35 insertions(+), 27 deletions(-) diff -puN drivers/net/bonding/bond_main.c~bonding-fix-lock-ordering-for-rtnl-and-bonding_rwsem drivers/net/bonding/bond_main.c --- a/drivers/net/bonding/bond_main.c~bonding-fix-lock-ordering-for-rtnl-and-bonding_rwsem +++ a/drivers/net/bonding/bond_main.c @@ -4874,9 +4874,22 @@ static struct lock_class_key bonding_net 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_ 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 -puN drivers/net/bonding/bond_sysfs.c~bonding-fix-lock-ordering-for-rtnl-and-bonding_rwsem drivers/net/bonding/bond_sysfs.c --- a/drivers/net/bonding/bond_sysfs.c~bonding-fix-lock-ordering-for-rtnl-and-bonding_rwsem +++ a/drivers/net/bonding/bond_sysfs.c @@ -109,11 +109,10 @@ static ssize_t bonding_store_bonds(struc { 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(struc 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(struc ": %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(struc 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(stru /* 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(stru 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(stru 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) _ Patches currently in -mm which might be from fubar@xxxxxxxxxx are git-netdev-all.patch bonding-fix-locking-in-sysfs-primary-active-selection.patch bonding-fix-assert_rtnl-that-produces-spurious-warnings.patch bonding-fix-locking-during-alb-failover-and-slave-removal.patch bonding-release-slaves-when-master-removed-via-sysfs.patch bonding-fix-up-parameter-parsing.patch bonding-fix-lock-ordering-for-rtnl-and-bonding_rwsem.patch bonding-dont-hold-lock-when-calling-rtnl_unlock.patch - To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html