[PATCH 6.0 031/157] net/mlx5: Lag, avoid lockdep warnings

From: Eli Cohen elic@nvidia.com

[ Upstream commit 0d4e8ed139d871fcb2844dd71075997753baeec8 ]

ldev->lock is used to serialize lag change operations. Since multiport eswtich functionality was added, we now change the mode dynamically. However, acquiring ldev->lock is not allowed as it could possibly lead to a deadlock as reported by the lockdep mechanism.

[ 836.154963] WARNING: possible circular locking dependency detected [ 836.155850] 5.19.0-rc5_net_56b7df2 #1 Not tainted [ 836.156549] ------------------------------------------------------ [ 836.157418] handler1/12198 is trying to acquire lock: [ 836.158178] ffff888187d52b58 (&ldev->lock){+.+.}-{3:3}, at: mlx5_lag_do_mirred+0x3b/0x70 [mlx5_core] [ 836.159575] [ 836.159575] but task is already holding lock: [ 836.160474] ffff8881d4de2930 (&block->cb_lock){++++}-{3:3}, at: tc_setup_cb_add+0x5b/0x200 [ 836.161669] which lock already depends on the new lock. [ 836.162905] [ 836.162905] the existing dependency chain (in reverse order) is: [ 836.164008] -> #3 (&block->cb_lock){++++}-{3:3}: [ 836.164946] down_write+0x25/0x60 [ 836.165548] tcf_block_get_ext+0x1c6/0x5d0 [ 836.166253] ingress_init+0x74/0xa0 [sch_ingress] [ 836.167028] qdisc_create.constprop.0+0x130/0x5e0 [ 836.167805] tc_modify_qdisc+0x481/0x9f0 [ 836.168490] rtnetlink_rcv_msg+0x16e/0x5a0 [ 836.169189] netlink_rcv_skb+0x4e/0xf0 [ 836.169861] netlink_unicast+0x190/0x250 [ 836.170543] netlink_sendmsg+0x243/0x4b0 [ 836.171226] sock_sendmsg+0x33/0x40 [ 836.171860] ____sys_sendmsg+0x1d1/0x1f0 [ 836.172535] ___sys_sendmsg+0xab/0xf0 [ 836.173183] __sys_sendmsg+0x51/0x90 [ 836.173836] do_syscall_64+0x3d/0x90 [ 836.174471] entry_SYSCALL_64_after_hwframe+0x46/0xb0 [ 836.175282]

[ 836.175282] -> #2 (rtnl_mutex){+.+.}-{3:3}: [ 836.176190] __mutex_lock+0x6b/0xf80 [ 836.176830] register_netdevice_notifier+0x21/0x120 [ 836.177631] rtnetlink_init+0x2d/0x1e9 [ 836.178289] netlink_proto_init+0x163/0x179 [ 836.178994] do_one_initcall+0x63/0x300 [ 836.179672] kernel_init_freeable+0x2cb/0x31b [ 836.180403] kernel_init+0x17/0x140 [ 836.181035] ret_from_fork+0x1f/0x30

[ 836.181687] -> #1 (pernet_ops_rwsem){+.+.}-{3:3}: [ 836.182628] down_write+0x25/0x60 [ 836.183235] unregister_netdevice_notifier+0x1c/0xb0 [ 836.184029] mlx5_ib_roce_cleanup+0x94/0x120 [mlx5_ib] [ 836.184855] __mlx5_ib_remove+0x35/0x60 [mlx5_ib] [ 836.185637] mlx5_eswitch_unregister_vport_reps+0x22f/0x440 [mlx5_core] [ 836.186698] auxiliary_bus_remove+0x18/0x30 [ 836.187409] device_release_driver_internal+0x1f6/0x270 [ 836.188253] bus_remove_device+0xef/0x160 [ 836.188939] device_del+0x18b/0x3f0 [ 836.189562] mlx5_rescan_drivers_locked+0xd6/0x2d0 [mlx5_core] [ 836.190516] mlx5_lag_remove_devices+0x69/0xe0 [mlx5_core] [ 836.191414] mlx5_do_bond_work+0x441/0x620 [mlx5_core] [ 836.192278] process_one_work+0x25c/0x590 [ 836.192963] worker_thread+0x4f/0x3d0 [ 836.193609] kthread+0xcb/0xf0 [ 836.194189] ret_from_fork+0x1f/0x30

[ 836.194826] -> #0 (&ldev->lock){+.+.}-{3:3}: [ 836.195734] __lock_acquire+0x15b8/0x2a10 [ 836.196426] lock_acquire+0xce/0x2d0 [ 836.197057] __mutex_lock+0x6b/0xf80 [ 836.197708] mlx5_lag_do_mirred+0x3b/0x70 [mlx5_core] [ 836.198575] tc_act_parse_mirred+0x25b/0x800 [mlx5_core] [ 836.199467] parse_tc_actions+0x168/0x5a0 [mlx5_core] [ 836.200340] __mlx5e_add_fdb_flow+0x263/0x480 [mlx5_core] [ 836.201241] mlx5e_configure_flower+0x8a0/0x1820 [mlx5_core] [ 836.202187] tc_setup_cb_add+0xd7/0x200 [ 836.202856] fl_hw_replace_filter+0x14c/0x1f0 [cls_flower] [ 836.203739] fl_change+0xbbe/0x1730 [cls_flower] [ 836.204501] tc_new_tfilter+0x407/0xd90 [ 836.205168] rtnetlink_rcv_msg+0x406/0x5a0 [ 836.205877] netlink_rcv_skb+0x4e/0xf0 [ 836.206535] netlink_unicast+0x190/0x250 [ 836.207217] netlink_sendmsg+0x243/0x4b0 [ 836.207915] sock_sendmsg+0x33/0x40 [ 836.208538] ____sys_sendmsg+0x1d1/0x1f0 [ 836.209219] ___sys_sendmsg+0xab/0xf0 [ 836.209878] __sys_sendmsg+0x51/0x90 [ 836.210510] do_syscall_64+0x3d/0x90 [ 836.211137] entry_SYSCALL_64_after_hwframe+0x46/0xb0

[ 836.211954] other info that might help us debug this: [ 836.213174] Chain exists of: [ 836.213174] &ldev->lock --> rtnl_mutex --> &block->cb_lock 836.214650] Possible unsafe locking scenario: [ 836.214650] [ 836.215574] CPU0 CPU1 [ 836.216255] ---- ---- [ 836.216943] lock(&block->cb_lock); [ 836.217518] lock(rtnl_mutex); [ 836.218348] lock(&block->cb_lock); [ 836.219212] lock(&ldev->lock); [ 836.219758] [ 836.219758] *** DEADLOCK *** [ 836.219758] [ 836.220747] 2 locks held by handler1/12198: [ 836.221390] #0: ffff8881d4de2930 (&block->cb_lock){++++}-{3:3}, at: tc_setup_cb_add+0x5b/0x200 [ 836.222646] #1: ffff88810c9a92c0 (&esw->mode_lock){++++}-{3:3}, at: mlx5_esw_hold+0x39/0x50 [mlx5_core]

[ 836.224063] stack backtrace: [ 836.224799] CPU: 6 PID: 12198 Comm: handler1 Not tainted 5.19.0-rc5_net_56b7df2 #1 [ 836.225923] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 [ 836.227476] Call Trace: [ 836.227929] <TASK> [ 836.228332] dump_stack_lvl+0x57/0x7d [ 836.228924] check_noncircular+0x104/0x120 [ 836.229562] __lock_acquire+0x15b8/0x2a10 [ 836.230201] lock_acquire+0xce/0x2d0 [ 836.230776] ? mlx5_lag_do_mirred+0x3b/0x70 [mlx5_core] [ 836.231614] ? find_held_lock+0x2b/0x80 [ 836.232221] __mutex_lock+0x6b/0xf80 [ 836.232799] ? mlx5_lag_do_mirred+0x3b/0x70 [mlx5_core] [ 836.233636] ? mlx5_lag_do_mirred+0x3b/0x70 [mlx5_core] [ 836.234451] ? xa_load+0xc3/0x190 [ 836.234995] mlx5_lag_do_mirred+0x3b/0x70 [mlx5_core] [ 836.235803] tc_act_parse_mirred+0x25b/0x800 [mlx5_core] [ 836.236636] ? tc_act_can_offload_mirred+0x135/0x210 [mlx5_core] [ 836.237550] parse_tc_actions+0x168/0x5a0 [mlx5_core] [ 836.238364] __mlx5e_add_fdb_flow+0x263/0x480 [mlx5_core] [ 836.239202] mlx5e_configure_flower+0x8a0/0x1820 [mlx5_core] [ 836.240076] ? lock_acquire+0xce/0x2d0 [ 836.240668] ? tc_setup_cb_add+0x5b/0x200 [ 836.241294] tc_setup_cb_add+0xd7/0x200 [ 836.241917] fl_hw_replace_filter+0x14c/0x1f0 [cls_flower] [ 836.242709] fl_change+0xbbe/0x1730 [cls_flower] [ 836.243408] tc_new_tfilter+0x407/0xd90 [ 836.244043] ? tc_del_tfilter+0x880/0x880 [ 836.244672] rtnetlink_rcv_msg+0x406/0x5a0 [ 836.245310] ? netlink_deliver_tap+0x7a/0x4b0 [ 836.245991] ? if_nlmsg_stats_size+0x2b0/0x2b0 [ 836.246675] netlink_rcv_skb+0x4e/0xf0 [ 836.258046] netlink_unicast+0x190/0x250 [ 836.258669] netlink_sendmsg+0x243/0x4b0 [ 836.259288] sock_sendmsg+0x33/0x40 [ 836.259857] ____sys_sendmsg+0x1d1/0x1f0 [ 836.260473] ___sys_sendmsg+0xab/0xf0 [ 836.261064] ? lock_acquire+0xce/0x2d0 [ 836.261669] ? find_held_lock+0x2b/0x80 [ 836.262272] ? __fget_files+0xb9/0x190 [ 836.262871] ? __fget_files+0xd3/0x190 [ 836.263462] __sys_sendmsg+0x51/0x90 [ 836.264064] do_syscall_64+0x3d/0x90 [ 836.264652] entry_SYSCALL_64_after_hwframe+0x46/0xb0 [ 836.265425] RIP: 0033:0x7fdbe5e2677d

[ 836.266012] Code: 28 89 54 24 1c 48 89 74 24 10 89 7c 24 08 e8 ba ee ff ff 8b 54 24 1c 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 33 44 89 c7 48 89 44 24 08 e8 ee ee ff ff 48 [ 836.268485] RSP: 002b:00007fdbe48a75a0 EFLAGS: 00000293 ORIG_RAX: 000000000000002e [ 836.269598] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007fdbe5e2677d [ 836.270576] RDX: 0000000000000000 RSI: 00007fdbe48a7640 RDI: 000000000000003c [ 836.271565] RBP: 00007fdbe48a8368 R08: 0000000000000000 R09: 0000000000000000 [ 836.272546] R10: 00007fdbe48a84b0 R11: 0000000000000293 R12: 0000557bd17dc860 [ 836.273527] R13: 0000000000000000 R14: 0000557bd17dc860 R15: 00007fdbe48a7640

[ 836.274521] </TASK>

To avoid using mode holding ldev->lock in the configure flow, we queue a work to the lag workqueue and cease wait on a completion object.

In addition, we remove the lock from mlx5_lag_do_mirred() since it is not really protecting anything.

It should be noted that an actual deadlock has not been observed.

Signed-off-by: Eli Cohen elic@nvidia.com Reviewed-by: Mark Bloch mbloch@nvidia.com Signed-off-by: Saeed Mahameed saeedm@nvidia.com Signed-off-by: Sasha Levin sashal@kernel.org --- .../net/ethernet/mellanox/mlx5/core/lag/lag.c | 3 +- .../net/ethernet/mellanox/mlx5/core/lag/lag.h | 14 ++- .../ethernet/mellanox/mlx5/core/lag/mpesw.c | 100 +++++++++++------- .../ethernet/mellanox/mlx5/core/lag/mpesw.h | 1 - 4 files changed, 78 insertions(+), 40 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c index 48f86e12f5c0..bbe810f3b373 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c @@ -201,9 +201,8 @@ static void mlx5_ldev_free(struct kref *ref) if (ldev->nb.notifier_call) unregister_netdevice_notifier_net(&init_net, &ldev->nb); mlx5_lag_mp_cleanup(ldev); - mlx5_lag_mpesw_cleanup(ldev); - cancel_work_sync(&ldev->mpesw_work); destroy_workqueue(ldev->wq); + mlx5_lag_mpesw_cleanup(ldev); mutex_destroy(&ldev->lock); kfree(ldev); } diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.h b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.h index ce2ce8ccbd70..f30ac2de639f 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.h +++ b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.h @@ -50,6 +50,19 @@ struct lag_tracker { enum netdev_lag_hash hash_type; };

+enum mpesw_op { + MLX5_MPESW_OP_ENABLE, + MLX5_MPESW_OP_DISABLE, +}; + +struct mlx5_mpesw_work_st { + struct work_struct work; + struct mlx5_lag *lag; + enum mpesw_op op; + struct completion comp; + int result; +}; + /* LAG data of a ConnectX card. * It serves both its phys functions. */ @@ -66,7 +79,6 @@ struct mlx5_lag { struct lag_tracker tracker; struct workqueue_struct *wq; struct delayed_work bond_work; - struct work_struct mpesw_work; struct notifier_block nb; struct lag_mp lag_mp; struct mlx5_lag_port_sel port_sel; diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lag/mpesw.c b/drivers/net/ethernet/mellanox/mlx5/core/lag/mpesw.c index f643202b29c6..c17e8f1ec914 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/lag/mpesw.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/lag/mpesw.c @@ -7,63 +7,95 @@ #include "eswitch.h" #include "lib/mlx5.h"

-void mlx5_mpesw_work(struct work_struct *work) +static int add_mpesw_rule(struct mlx5_lag *ldev) { - struct mlx5_lag *ldev = container_of(work, struct mlx5_lag, mpesw_work); + struct mlx5_core_dev *dev = ldev->pf[MLX5_LAG_P1].dev; + int err;

- mutex_lock(&ldev->lock); - mlx5_disable_lag(ldev); - mutex_unlock(&ldev->lock); -} + if (atomic_add_return(1, &ldev->lag_mpesw.mpesw_rule_count) != 1) + return 0;

-static void mlx5_lag_disable_mpesw(struct mlx5_core_dev *dev) -{ - struct mlx5_lag *ldev = dev->priv.lag; + if (ldev->mode != MLX5_LAG_MODE_NONE) { + err = -EINVAL; + goto out_err; + }

- if (!queue_work(ldev->wq, &ldev->mpesw_work)) - mlx5_core_warn(dev, "failed to queue work\n"); + err = mlx5_activate_lag(ldev, NULL, MLX5_LAG_MODE_MPESW, false); + if (err) { + mlx5_core_warn(dev, "Failed to create LAG in MPESW mode (%d)\n", err); + goto out_err; + } + + return 0; + +out_err: + atomic_dec(&ldev->lag_mpesw.mpesw_rule_count); + return err; }

-void mlx5_lag_del_mpesw_rule(struct mlx5_core_dev *dev) +static void del_mpesw_rule(struct mlx5_lag *ldev) { - struct mlx5_lag *ldev = dev->priv.lag; + if (!atomic_dec_return(&ldev->lag_mpesw.mpesw_rule_count) && + ldev->mode == MLX5_LAG_MODE_MPESW) + mlx5_disable_lag(ldev); +}

- if (!ldev) - return; +static void mlx5_mpesw_work(struct work_struct *work) +{ + struct mlx5_mpesw_work_st *mpesww = container_of(work, struct mlx5_mpesw_work_st, work); + struct mlx5_lag *ldev = mpesww->lag;

mutex_lock(&ldev->lock); - if (!atomic_dec_return(&ldev->lag_mpesw.mpesw_rule_count) && - ldev->mode == MLX5_LAG_MODE_MPESW) - mlx5_lag_disable_mpesw(dev); + if (mpesww->op == MLX5_MPESW_OP_ENABLE) + mpesww->result = add_mpesw_rule(ldev); + else if (mpesww->op == MLX5_MPESW_OP_DISABLE) + del_mpesw_rule(ldev); mutex_unlock(&ldev->lock); + + complete(&mpesww->comp); }

-int mlx5_lag_add_mpesw_rule(struct mlx5_core_dev *dev) +static int mlx5_lag_mpesw_queue_work(struct mlx5_core_dev *dev, + enum mpesw_op op) { struct mlx5_lag *ldev = dev->priv.lag; + struct mlx5_mpesw_work_st *work; int err = 0;

if (!ldev) return 0;

- mutex_lock(&ldev->lock); - if (atomic_add_return(1, &ldev->lag_mpesw.mpesw_rule_count) != 1) - goto out; + work = kzalloc(sizeof(*work), GFP_KERNEL); + if (!work) + return -ENOMEM;

- if (ldev->mode != MLX5_LAG_MODE_NONE) { + INIT_WORK(&work->work, mlx5_mpesw_work); + init_completion(&work->comp); + work->op = op; + work->lag = ldev; + + if (!queue_work(ldev->wq, &work->work)) { + mlx5_core_warn(dev, "failed to queue mpesw work\n"); err = -EINVAL; goto out; } - - err = mlx5_activate_lag(ldev, NULL, MLX5_LAG_MODE_MPESW, false); - if (err) - mlx5_core_warn(dev, "Failed to create LAG in MPESW mode (%d)\n", err); - + wait_for_completion(&work->comp); + err = work->result; out: - mutex_unlock(&ldev->lock); + kfree(work); return err; }

+void mlx5_lag_del_mpesw_rule(struct mlx5_core_dev *dev) +{ + mlx5_lag_mpesw_queue_work(dev, MLX5_MPESW_OP_DISABLE); +} + +int mlx5_lag_add_mpesw_rule(struct mlx5_core_dev *dev) +{ + return mlx5_lag_mpesw_queue_work(dev, MLX5_MPESW_OP_ENABLE); +} + int mlx5_lag_do_mirred(struct mlx5_core_dev *mdev, struct net_device *out_dev) { struct mlx5_lag *ldev = mdev->priv.lag; @@ -71,12 +103,9 @@ int mlx5_lag_do_mirred(struct mlx5_core_dev *mdev, struct net_device *out_dev) if (!netif_is_bond_master(out_dev) || !ldev) return 0;

- mutex_lock(&ldev->lock); - if (ldev->mode == MLX5_LAG_MODE_MPESW) { - mutex_unlock(&ldev->lock); + if (ldev->mode == MLX5_LAG_MODE_MPESW) return -EOPNOTSUPP; - } - mutex_unlock(&ldev->lock); + return 0; }

@@ -90,11 +119,10 @@ bool mlx5_lag_mpesw_is_activated(struct mlx5_core_dev *dev)

void mlx5_lag_mpesw_init(struct mlx5_lag *ldev) { - INIT_WORK(&ldev->mpesw_work, mlx5_mpesw_work); atomic_set(&ldev->lag_mpesw.mpesw_rule_count, 0); }

void mlx5_lag_mpesw_cleanup(struct mlx5_lag *ldev) { - cancel_delayed_work_sync(&ldev->bond_work); + WARN_ON(atomic_read(&ldev->lag_mpesw.mpesw_rule_count)); } diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lag/mpesw.h b/drivers/net/ethernet/mellanox/mlx5/core/lag/mpesw.h index be4abcb8fcd5..88e8daffcf92 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/lag/mpesw.h +++ b/drivers/net/ethernet/mellanox/mlx5/core/lag/mpesw.h @@ -12,7 +12,6 @@ struct lag_mpesw { atomic_t mpesw_rule_count; };

-void mlx5_mpesw_work(struct work_struct *work); int mlx5_lag_do_mirred(struct mlx5_core_dev *mdev, struct net_device *out_dev); bool mlx5_lag_mpesw_is_activated(struct mlx5_core_dev *dev); #if IS_ENABLED(CONFIG_MLX5_ESWITCH)