[PATCH AUTOSEL 6.0 29/39] net/mlx5: Lag, avoid lockdep warnings

Sasha Levin
2022-11-28T17:41:45Z

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 065102278cb8..7e139df1305f 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)
--
2.35.1