bonding: change ipsec_lock from spin lock to mutex

In the cited commit, bond->ipsec_lock is added to protect ipsec_list,
hence xdo_dev_state_add and xdo_dev_state_delete are called inside
this lock. As ipsec_lock is a spin lock and such xfrmdev ops may sleep,
"scheduling while atomic" will be triggered when changing bond's
active slave.

[  101.055189] BUG: scheduling while atomic: bash/902/0x00000200
[  101.055726] Modules linked in:
[  101.058211] CPU: 3 PID: 902 Comm: bash Not tainted 6.9.0-rc4+ #1
[  101.058760] Hardware name:
[  101.059434] Call Trace:
[  101.059436]  <TASK>
[  101.060873]  dump_stack_lvl+0x51/0x60
[  101.061275]  __schedule_bug+0x4e/0x60
[  101.061682]  __schedule+0x612/0x7c0
[  101.062078]  ? __mod_timer+0x25c/0x370
[  101.062486]  schedule+0x25/0xd0
[  101.062845]  schedule_timeout+0x77/0xf0
[  101.063265]  ? asm_common_interrupt+0x22/0x40
[  101.063724]  ? __bpf_trace_itimer_state+0x10/0x10
[  101.064215]  __wait_for_common+0x87/0x190
[  101.064648]  ? usleep_range_state+0x90/0x90
[  101.065091]  cmd_exec+0x437/0xb20 [mlx5_core]
[  101.065569]  mlx5_cmd_do+0x1e/0x40 [mlx5_core]
[  101.066051]  mlx5_cmd_exec+0x18/0x30 [mlx5_core]
[  101.066552]  mlx5_crypto_create_dek_key+0xea/0x120 [mlx5_core]
[  101.067163]  ? bonding_sysfs_store_option+0x4d/0x80 [bonding]
[  101.067738]  ? kmalloc_trace+0x4d/0x350
[  101.068156]  mlx5_ipsec_create_sa_ctx+0x33/0x100 [mlx5_core]
[  101.068747]  mlx5e_xfrm_add_state+0x47b/0xaa0 [mlx5_core]
[  101.069312]  bond_change_active_slave+0x392/0x900 [bonding]
[  101.069868]  bond_option_active_slave_set+0x1c2/0x240 [bonding]
[  101.070454]  __bond_opt_set+0xa6/0x430 [bonding]
[  101.070935]  __bond_opt_set_notify+0x2f/0x90 [bonding]
[  101.071453]  bond_opt_tryset_rtnl+0x72/0xb0 [bonding]
[  101.071965]  bonding_sysfs_store_option+0x4d/0x80 [bonding]
[  101.072567]  kernfs_fop_write_iter+0x10c/0x1a0
[  101.073033]  vfs_write+0x2d8/0x400
[  101.073416]  ? alloc_fd+0x48/0x180
[  101.073798]  ksys_write+0x5f/0xe0
[  101.074175]  do_syscall_64+0x52/0x110
[  101.074576]  entry_SYSCALL_64_after_hwframe+0x4b/0x53

As bond_ipsec_add_sa_all and bond_ipsec_del_sa_all are only called
from bond_change_active_slave, which requires holding the RTNL lock.
And bond_ipsec_add_sa and bond_ipsec_del_sa are xfrm state
xdo_dev_state_add and xdo_dev_state_delete APIs, which are in user
context. So ipsec_lock doesn't have to be spin lock, change it to
mutex, and thus the above issue can be resolved.

Fixes: 9a560550 ("bonding: Add struct bond_ipesc to manage SA")
Signed-off-by: Jianbo Liu <jianbol@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
Acked-by: Jay Vosburgh <jv@jvosburgh.net>
Link: https://patch.msgid.link/20240823031056.110999-4-jianbol@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/bonding/bond_main.c

@@ -428,6 +428,7 @@ static int bond_ipsec_add_sa(struct xfrm_state *xs,
 {
 	struct net_device *bond_dev = xs->xso.dev;
 	struct net_device *real_dev;
+	netdevice_tracker tracker;
 	struct bond_ipsec *ipsec;
 	struct bonding *bond;
 	struct slave *slave;
@@ -439,24 +440,26 @@ static int bond_ipsec_add_sa(struct xfrm_state *xs,
 	rcu_read_lock();
 	bond = netdev_priv(bond_dev);
 	slave = rcu_dereference(bond->curr_active_slave);
-	if (!slave) {
-		rcu_read_unlock();
-		return -ENODEV;
+	real_dev = slave ? slave->dev : NULL;
+	netdev_hold(real_dev, &tracker, GFP_ATOMIC);
+	rcu_read_unlock();
+	if (!real_dev) {
+		err = -ENODEV;
+		goto out;
 	}
 
-	real_dev = slave->dev;
 	if (!real_dev->xfrmdev_ops ||
 	    !real_dev->xfrmdev_ops->xdo_dev_state_add ||
 	    netif_is_bond_master(real_dev)) {
 		NL_SET_ERR_MSG_MOD(extack, "Slave does not support ipsec offload");
-		rcu_read_unlock();
-		return -EINVAL;
+		err = -EINVAL;
+		goto out;
 	}
 
-	ipsec = kmalloc(sizeof(*ipsec), GFP_ATOMIC);
+	ipsec = kmalloc(sizeof(*ipsec), GFP_KERNEL);
 	if (!ipsec) {
-		rcu_read_unlock();
-		return -ENOMEM;
+		err = -ENOMEM;
+		goto out;
 	}
 
 	xs->xso.real_dev = real_dev;
@@ -464,13 +467,14 @@ static int bond_ipsec_add_sa(struct xfrm_state *xs,
 	if (!err) {
 		ipsec->xs = xs;
 		INIT_LIST_HEAD(&ipsec->list);
-		spin_lock_bh(&bond->ipsec_lock);
+		mutex_lock(&bond->ipsec_lock);
 		list_add(&ipsec->list, &bond->ipsec_list);
-		spin_unlock_bh(&bond->ipsec_lock);
+		mutex_unlock(&bond->ipsec_lock);
 	} else {
 		kfree(ipsec);
 	}
-	rcu_read_unlock();
+out:
+	netdev_put(real_dev, &tracker);
 	return err;
 }
 
@@ -481,35 +485,35 @@ static void bond_ipsec_add_sa_all(struct bonding *bond)
 	struct bond_ipsec *ipsec;
 	struct slave *slave;
 
-	rcu_read_lock();
-	slave = rcu_dereference(bond->curr_active_slave);
-	if (!slave)
-		goto out;
+	slave = rtnl_dereference(bond->curr_active_slave);
+	real_dev = slave ? slave->dev : NULL;
+	if (!real_dev)
+		return;
 
-	real_dev = slave->dev;
+	mutex_lock(&bond->ipsec_lock);
 	if (!real_dev->xfrmdev_ops ||
 	    !real_dev->xfrmdev_ops->xdo_dev_state_add ||
 	    netif_is_bond_master(real_dev)) {
-		spin_lock_bh(&bond->ipsec_lock);
 		if (!list_empty(&bond->ipsec_list))
 			slave_warn(bond_dev, real_dev,
 				   "%s: no slave xdo_dev_state_add\n",
 				   __func__);
-		spin_unlock_bh(&bond->ipsec_lock);
 		goto out;
 	}
 
-	spin_lock_bh(&bond->ipsec_lock);
 	list_for_each_entry(ipsec, &bond->ipsec_list, list) {
+		/* If new state is added before ipsec_lock acquired */
+		if (ipsec->xs->xso.real_dev == real_dev)
+			continue;
+
 		ipsec->xs->xso.real_dev = real_dev;
 		if (real_dev->xfrmdev_ops->xdo_dev_state_add(ipsec->xs, NULL)) {
 			slave_warn(bond_dev, real_dev, "%s: failed to add SA\n", __func__);
 			ipsec->xs->xso.real_dev = NULL;
 		}
 	}
-	spin_unlock_bh(&bond->ipsec_lock);
 out:
-	rcu_read_unlock();
+	mutex_unlock(&bond->ipsec_lock);
 }
 
 /**
@@ -520,6 +524,7 @@ static void bond_ipsec_del_sa(struct xfrm_state *xs)
 {
 	struct net_device *bond_dev = xs->xso.dev;
 	struct net_device *real_dev;
+	netdevice_tracker tracker;
 	struct bond_ipsec *ipsec;
 	struct bonding *bond;
 	struct slave *slave;
@@ -530,6 +535,9 @@ static void bond_ipsec_del_sa(struct xfrm_state *xs)
 	rcu_read_lock();
 	bond = netdev_priv(bond_dev);
 	slave = rcu_dereference(bond->curr_active_slave);
+	real_dev = slave ? slave->dev : NULL;
+	netdev_hold(real_dev, &tracker, GFP_ATOMIC);
+	rcu_read_unlock();
 
 	if (!slave)
 		goto out;
@@ -537,7 +545,6 @@ static void bond_ipsec_del_sa(struct xfrm_state *xs)
 	if (!xs->xso.real_dev)
 		goto out;
 
-	real_dev = slave->dev;
 	WARN_ON(xs->xso.real_dev != real_dev);
 
 	if (!real_dev->xfrmdev_ops ||
@@ -549,7 +556,8 @@ static void bond_ipsec_del_sa(struct xfrm_state *xs)
 
 	real_dev->xfrmdev_ops->xdo_dev_state_delete(xs);
 out:
-	spin_lock_bh(&bond->ipsec_lock);
+	netdev_put(real_dev, &tracker);
+	mutex_lock(&bond->ipsec_lock);
 	list_for_each_entry(ipsec, &bond->ipsec_list, list) {
 		if (ipsec->xs == xs) {
 			list_del(&ipsec->list);
@@ -557,8 +565,7 @@ static void bond_ipsec_del_sa(struct xfrm_state *xs)
 			break;
 		}
 	}
-	spin_unlock_bh(&bond->ipsec_lock);
-	rcu_read_unlock();
+	mutex_unlock(&bond->ipsec_lock);
 }
 
 static void bond_ipsec_del_sa_all(struct bonding *bond)
@@ -568,15 +575,12 @@ static void bond_ipsec_del_sa_all(struct bonding *bond)
 	struct bond_ipsec *ipsec;
 	struct slave *slave;
 
-	rcu_read_lock();
-	slave = rcu_dereference(bond->curr_active_slave);
-	if (!slave) {
-		rcu_read_unlock();
+	slave = rtnl_dereference(bond->curr_active_slave);
+	real_dev = slave ? slave->dev : NULL;
+	if (!real_dev)
 		return;
-	}
 
-	real_dev = slave->dev;
-	spin_lock_bh(&bond->ipsec_lock);
+	mutex_lock(&bond->ipsec_lock);
 	list_for_each_entry(ipsec, &bond->ipsec_list, list) {
 		if (!ipsec->xs->xso.real_dev)
 			continue;
@@ -593,8 +597,7 @@ static void bond_ipsec_del_sa_all(struct bonding *bond)
 				real_dev->xfrmdev_ops->xdo_dev_state_free(ipsec->xs);
 		}
 	}
-	spin_unlock_bh(&bond->ipsec_lock);
-	rcu_read_unlock();
+	mutex_unlock(&bond->ipsec_lock);
 }
 
 static void bond_ipsec_free_sa(struct xfrm_state *xs)
@@ -5921,7 +5924,7 @@ void bond_setup(struct net_device *bond_dev)
 	/* set up xfrm device ops (only supported in active-backup right now) */
 	bond_dev->xfrmdev_ops = &bond_xfrmdev_ops;
 	INIT_LIST_HEAD(&bond->ipsec_list);
-	spin_lock_init(&bond->ipsec_lock);
+	mutex_init(&bond->ipsec_lock);
 #endif /* CONFIG_XFRM_OFFLOAD */
 
 	/* don't acquire bond device's netif_tx_lock when transmitting */
@@ -5970,6 +5973,10 @@ static void bond_uninit(struct net_device *bond_dev)
 		__bond_release_one(bond_dev, slave->dev, true, true);
 	netdev_info(bond_dev, "Released all slaves\n");
 
+#ifdef CONFIG_XFRM_OFFLOAD
+	mutex_destroy(&bond->ipsec_lock);
+#endif /* CONFIG_XFRM_OFFLOAD */
+
 	bond_set_slave_arr(bond, NULL, NULL);
 
 	list_del_rcu(&bond->bond_list);

include/net/bonding.h

@@ -260,7 +260,7 @@ struct bonding {
 #ifdef CONFIG_XFRM_OFFLOAD
 	struct list_head ipsec_list;
 	/* protecting ipsec_list */
-	spinlock_t ipsec_lock;
+	struct mutex ipsec_lock;
 #endif /* CONFIG_XFRM_OFFLOAD */
 	struct bpf_prog *xdp_prog;
 };