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net/mlx5: Avoid false positive lockdep warning by adding lock_class_key
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[ Upstream commit d59b73a ]

Add a lock_class_key per mlx5 device to avoid a false positive
"possible circular locking dependency" warning by lockdep, on flows
which lock more than one mlx5 device, such as adding SF.

kernel log:
 ======================================================
 WARNING: possible circular locking dependency detected
 5.19.0-rc8+ #2 Not tainted
 ------------------------------------------------------
 kworker/u20:0/8 is trying to acquire lock:
 ffff88812dfe0d98 (&dev->intf_state_mutex){+.+.}-{3:3}, at: mlx5_init_one+0x2e/0x490 [mlx5_core]

 but task is already holding lock:
 ffff888101aa7898 (&(&notifier->n_head)->rwsem){++++}-{3:3}, at: blocking_notifier_call_chain+0x5a/0x130

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 -> #1 (&(&notifier->n_head)->rwsem){++++}-{3:3}:
        down_write+0x90/0x150
        blocking_notifier_chain_register+0x53/0xa0
        mlx5_sf_table_init+0x369/0x4a0 [mlx5_core]
        mlx5_init_one+0x261/0x490 [mlx5_core]
        probe_one+0x430/0x680 [mlx5_core]
        local_pci_probe+0xd6/0x170
        work_for_cpu_fn+0x4e/0xa0
        process_one_work+0x7c2/0x1340
        worker_thread+0x6f6/0xec0
        kthread+0x28f/0x330
        ret_from_fork+0x1f/0x30

 -> #0 (&dev->intf_state_mutex){+.+.}-{3:3}:
        __lock_acquire+0x2fc7/0x6720
        lock_acquire+0x1c1/0x550
        __mutex_lock+0x12c/0x14b0
        mlx5_init_one+0x2e/0x490 [mlx5_core]
        mlx5_sf_dev_probe+0x29c/0x370 [mlx5_core]
        auxiliary_bus_probe+0x9d/0xe0
        really_probe+0x1e0/0xaa0
        __driver_probe_device+0x219/0x480
        driver_probe_device+0x49/0x130
        __device_attach_driver+0x1b8/0x280
        bus_for_each_drv+0x123/0x1a0
        __device_attach+0x1a3/0x460
        bus_probe_device+0x1a2/0x260
        device_add+0x9b1/0x1b40
        __auxiliary_device_add+0x88/0xc0
        mlx5_sf_dev_state_change_handler+0x67e/0x9d0 [mlx5_core]
        blocking_notifier_call_chain+0xd5/0x130
        mlx5_vhca_state_work_handler+0x2b0/0x3f0 [mlx5_core]
        process_one_work+0x7c2/0x1340
        worker_thread+0x59d/0xec0
        kthread+0x28f/0x330
        ret_from_fork+0x1f/0x30

  other info that might help us debug this:

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&(&notifier->n_head)->rwsem);
                                lock(&dev->intf_state_mutex);
                                lock(&(&notifier->n_head)->rwsem);
   lock(&dev->intf_state_mutex);

  *** DEADLOCK ***

 4 locks held by kworker/u20:0/8:
  #0: ffff888150612938 ((wq_completion)mlx5_events){+.+.}-{0:0}, at: process_one_work+0x6e2/0x1340
  #1: ffff888100cafdb8 ((work_completion)(&work->work)#3){+.+.}-{0:0}, at: process_one_work+0x70f/0x1340
  #2: ffff888101aa7898 (&(&notifier->n_head)->rwsem){++++}-{3:3}, at: blocking_notifier_call_chain+0x5a/0x130
  #3: ffff88813682d0e8 (&dev->mutex){....}-{3:3}, at:__device_attach+0x76/0x460

 stack backtrace:
 CPU: 6 PID: 8 Comm: kworker/u20:0 Not tainted 5.19.0-rc8+
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
 Workqueue: mlx5_events mlx5_vhca_state_work_handler [mlx5_core]
 Call Trace:
  <TASK>
  dump_stack_lvl+0x57/0x7d
  check_noncircular+0x278/0x300
  ? print_circular_bug+0x460/0x460
  ? lock_chain_count+0x20/0x20
  ? register_lock_class+0x1880/0x1880
  __lock_acquire+0x2fc7/0x6720
  ? register_lock_class+0x1880/0x1880
  ? register_lock_class+0x1880/0x1880
  lock_acquire+0x1c1/0x550
  ? mlx5_init_one+0x2e/0x490 [mlx5_core]
  ? lockdep_hardirqs_on_prepare+0x400/0x400
  __mutex_lock+0x12c/0x14b0
  ? mlx5_init_one+0x2e/0x490 [mlx5_core]
  ? mlx5_init_one+0x2e/0x490 [mlx5_core]
  ? _raw_read_unlock+0x1f/0x30
  ? mutex_lock_io_nested+0x1320/0x1320
  ? __ioremap_caller.constprop.0+0x306/0x490
  ? mlx5_sf_dev_probe+0x269/0x370 [mlx5_core]
  ? iounmap+0x160/0x160
  mlx5_init_one+0x2e/0x490 [mlx5_core]
  mlx5_sf_dev_probe+0x29c/0x370 [mlx5_core]
  ? mlx5_sf_dev_remove+0x130/0x130 [mlx5_core]
  auxiliary_bus_probe+0x9d/0xe0
  really_probe+0x1e0/0xaa0
  __driver_probe_device+0x219/0x480
  ? auxiliary_match_id+0xe9/0x140
  driver_probe_device+0x49/0x130
  __device_attach_driver+0x1b8/0x280
  ? driver_allows_async_probing+0x140/0x140
  bus_for_each_drv+0x123/0x1a0
  ? bus_for_each_dev+0x1a0/0x1a0
  ? lockdep_hardirqs_on_prepare+0x286/0x400
  ? trace_hardirqs_on+0x2d/0x100
  __device_attach+0x1a3/0x460
  ? device_driver_attach+0x1e0/0x1e0
  ? kobject_uevent_env+0x22d/0xf10
  bus_probe_device+0x1a2/0x260
  device_add+0x9b1/0x1b40
  ? dev_set_name+0xab/0xe0
  ? __fw_devlink_link_to_suppliers+0x260/0x260
  ? memset+0x20/0x40
  ? lockdep_init_map_type+0x21a/0x7d0
  __auxiliary_device_add+0x88/0xc0
  ? auxiliary_device_init+0x86/0xa0
  mlx5_sf_dev_state_change_handler+0x67e/0x9d0 [mlx5_core]
  blocking_notifier_call_chain+0xd5/0x130
  mlx5_vhca_state_work_handler+0x2b0/0x3f0 [mlx5_core]
  ? mlx5_vhca_event_arm+0x100/0x100 [mlx5_core]
  ? lock_downgrade+0x6e0/0x6e0
  ? lockdep_hardirqs_on_prepare+0x286/0x400
  process_one_work+0x7c2/0x1340
  ? lockdep_hardirqs_on_prepare+0x400/0x400
  ? pwq_dec_nr_in_flight+0x230/0x230
  ? rwlock_bug.part.0+0x90/0x90
  worker_thread+0x59d/0xec0
  ? process_one_work+0x1340/0x1340
  kthread+0x28f/0x330
  ? kthread_complete_and_exit+0x20/0x20
  ret_from_fork+0x1f/0x30
  </TASK>

Fixes: 6a32732 ("net/mlx5: SF, Port function state change support")
Signed-off-by: Moshe Shemesh <[email protected]>
Reviewed-by: Shay Drory <[email protected]>
Signed-off-by: Saeed Mahameed <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
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@mosheshemesh2 @gregkh
mosheshemesh2 authored and gregkh committed Aug 31, 2022
1 parent 0782959 commit e161c24
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Showing 2 changed files with 5 additions and 0 deletions.
4 changes: 4 additions & 0 deletions drivers/net/ethernet/mellanox/mlx5/core/main.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1427,7 +1427,9 @@ int mlx5_mdev_init(struct mlx5_core_dev *dev, int profile_idx)
memcpy(&dev->profile, &profile[profile_idx], sizeof(dev->profile));
INIT_LIST_HEAD(&priv->ctx_list);
spin_lock_init(&priv->ctx_lock);
lockdep_register_key(&dev->lock_key);
mutex_init(&dev->intf_state_mutex);
lockdep_set_class(&dev->intf_state_mutex, &dev->lock_key);

mutex_init(&priv->bfregs.reg_head.lock);
mutex_init(&priv->bfregs.wc_head.lock);
Expand Down Expand Up @@ -1474,6 +1476,7 @@ int mlx5_mdev_init(struct mlx5_core_dev *dev, int profile_idx)
mutex_destroy(&priv->bfregs.wc_head.lock);
mutex_destroy(&priv->bfregs.reg_head.lock);
mutex_destroy(&dev->intf_state_mutex);
lockdep_unregister_key(&dev->lock_key);
return err;
}

Expand All @@ -1491,6 +1494,7 @@ void mlx5_mdev_uninit(struct mlx5_core_dev *dev)
mutex_destroy(&priv->bfregs.wc_head.lock);
mutex_destroy(&priv->bfregs.reg_head.lock);
mutex_destroy(&dev->intf_state_mutex);
lockdep_unregister_key(&dev->lock_key);
}

static int probe_one(struct pci_dev *pdev, const struct pci_device_id *id)
Expand Down
1 change: 1 addition & 0 deletions include/linux/mlx5/driver.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -759,6 +759,7 @@ struct mlx5_core_dev {
enum mlx5_device_state state;
/* sync interface state */
struct mutex intf_state_mutex;
struct lock_class_key lock_key;
unsigned long intf_state;
struct mlx5_priv priv;
struct mlx5_profile profile;
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