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bonding: use dynamic lockdep key instead of subclass 

All bonding device has same lockdep key and subclass is initialized with
nest_level.
But actual nest_level value can be changed when a lower device is attached.
And at this moment, the subclass should be updated but it seems to be
unsafe.
So this patch makes bonding use dynamic lockdep key instead of the
subclass.

Test commands:
    ip link add bond0 type bond

    for i in {1..5}
    do
	    let A=$i-1
	    ip link add bond$i type bond
	    ip link set bond$i master bond$A
    done
    ip link set bond5 master bond0

Splat looks like:
[  307.992912] WARNING: possible recursive locking detected
[  307.993656] 5.4.0-rc3+ #96 Tainted: G        W
[  307.994367] --------------------------------------------
[  307.995092] ip/761 is trying to acquire lock:
[  307.995710] ffff8880513aac60 (&(&bond->stats_lock)->rlock#2/2){+.+.}, at: bond_get_stats+0xb8/0x500 [bonding]
[  307.997045]
	       but task is already holding lock:
[  307.997923] ffff88805fcbac60 (&(&bond->stats_lock)->rlock#2/2){+.+.}, at: bond_get_stats+0xb8/0x500 [bonding]
[  307.999215]
	       other info that might help us debug this:
[  308.000251]  Possible unsafe locking scenario:

[  308.001137]        CPU0
[  308.001533]        ----
[  308.001915]   lock(&(&bond->stats_lock)->rlock#2/2);
[  308.002609]   lock(&(&bond->stats_lock)->rlock#2/2);
[  308.003302]
		*** DEADLOCK ***

[  308.004310]  May be due to missing lock nesting notation

[  308.005319] 3 locks held by ip/761:
[  308.005830]  #0: ffffffff9fcc42b0 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x466/0x8a0
[  308.006894]  #1: ffff88805fcbac60 (&(&bond->stats_lock)->rlock#2/2){+.+.}, at: bond_get_stats+0xb8/0x500 [bonding]
[  308.008243]  #2: ffffffff9f9219c0 (rcu_read_lock){....}, at: bond_get_stats+0x9f/0x500 [bonding]
[  308.009422]
	       stack backtrace:
[  308.010124] CPU: 0 PID: 761 Comm: ip Tainted: G        W         5.4.0-rc3+ #96
[  308.011097] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[  308.012179] Call Trace:
[  308.012601]  dump_stack+0x7c/0xbb
[  308.013089]  __lock_acquire+0x269d/0x3de0
[  308.013669]  ? register_lock_class+0x14d0/0x14d0
[  308.014318]  lock_acquire+0x164/0x3b0
[  308.014858]  ? bond_get_stats+0xb8/0x500 [bonding]
[  308.015520]  _raw_spin_lock_nested+0x2e/0x60
[  308.016129]  ? bond_get_stats+0xb8/0x500 [bonding]
[  308.017215]  bond_get_stats+0xb8/0x500 [bonding]
[  308.018454]  ? bond_arp_rcv+0xf10/0xf10 [bonding]
[  308.019710]  ? rcu_read_lock_held+0x90/0xa0
[  308.020605]  ? rcu_read_lock_sched_held+0xc0/0xc0
[  308.021286]  ? bond_get_stats+0x9f/0x500 [bonding]
[  308.021953]  dev_get_stats+0x1ec/0x270
[  308.022508]  bond_get_stats+0x1d1/0x500 [bonding]

Fixes: d3fff6c443 ("net: add netdev_lockdep_set_classes() helper")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Taehee Yoo 2019-10-21 18:47:53 +00:00 committed by David S. Miller
parent 65de65d903
commit 089bca2cae
2 changed files with 8 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/net/bonding/bond_main.c
View File

@ -3459,7 +3459,7 @@ static void bond_get_stats(struct net_device *bond_dev,
struct list_head *iter;
struct slave *slave;
spin_lock_nested(&bond->stats_lock, bond_get_nest_level(bond_dev));
spin_lock(&bond->stats_lock);
memcpy(stats, &bond->bond_stats, sizeof(*stats));
rcu_read_lock();
@ -4297,8 +4297,6 @@ void bond_setup(struct net_device *bond_dev)
{
struct bonding *bond = netdev_priv(bond_dev);
spin_lock_init(&bond->mode_lock);
spin_lock_init(&bond->stats_lock);
bond->params = bonding_defaults;
/* Initialize pointers */
@ -4367,6 +4365,7 @@ static void bond_uninit(struct net_device *bond_dev)
list_del(&bond->bond_list);
lockdep_unregister_key(&bond->stats_lock_key);
bond_debug_unregister(bond);
}
@ -4772,6 +4771,11 @@ static int bond_init(struct net_device *bond_dev)
bond->nest_level = SINGLE_DEPTH_NESTING;
spin_lock_init(&bond->mode_lock);
spin_lock_init(&bond->stats_lock);
lockdep_register_key(&bond->stats_lock_key);
lockdep_set_class(&bond->stats_lock, &bond->stats_lock_key);
list_add_tail(&bond->bond_list, &bn->dev_list);
bond_prepare_sysfs_group(bond);

1
include/net/bonding.h
View File

@ -239,6 +239,7 @@ struct bonding {
struct dentry *debug_dir;
#endif /* CONFIG_DEBUG_FS */
struct rtnl_link_stats64 bond_stats;
struct lock_class_key stats_lock_key;
};
#define bond_slave_get_rcu(dev) \