[PATCH net] net/mlx4_en: initialize cmd.context_lock spinlock earlier

[Eric Dumazet]

From: Eric Dumazet <eduma...@google.com>

Maciej Żenczykowski reported lockdep warning a spinlock
was not registered before being held in mlx4_cmd_wake_completions()

cmd.context_lock initialization is not at the right place.

1) mlx4_cmd_use_events() can be called multiple times.
   Calling spin_lock_init() on a live spinlock can lead
   to hangs.

2) mlx4_cmd_wake_completions() can be called while lock
   has not been initialized.
   Lockdep complains, and current logic is not race prone.

It seems better to move the initialization earlier in
mlx4_load_one()

Signed-off-by: Eric Dumazet <eduma...@google.com>
Reported-by: Maciej Żenczykowski <m...@google.com>
Cc: Eugenia Emantayev <euge...@mellanox.com>
Cc: Tariq Toukan <tar...@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlx4/cmd.c  |    1 -
 drivers/net/ethernet/mellanox/mlx4/main.c |    1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/cmd.c 
b/drivers/net/ethernet/mellanox/mlx4/cmd.c
index e94ca1c3fc7c..f04a423ff79d 100644
--- a/drivers/net/ethernet/mellanox/mlx4/cmd.c
+++ b/drivers/net/ethernet/mellanox/mlx4/cmd.c
@@ -2597,7 +2597,6 @@ int mlx4_cmd_use_events(struct mlx4_dev *dev)
        priv->cmd.free_head = 0;
 
        sema_init(&priv->cmd.event_sem, priv->cmd.max_cmds);
-       spin_lock_init(&priv->cmd.context_lock);
 
        for (priv->cmd.token_mask = 1;
             priv->cmd.token_mask < priv->cmd.max_cmds;
diff --git a/drivers/net/ethernet/mellanox/mlx4/main.c 
b/drivers/net/ethernet/mellanox/mlx4/main.c
index 12c77a70abdb..372ebfa880f5 100644
--- a/drivers/net/ethernet/mellanox/mlx4/main.c
+++ b/drivers/net/ethernet/mellanox/mlx4/main.c
@@ -3222,6 +3222,7 @@ static int mlx4_load_one(struct pci_dev *pdev, int 
pci_dev_data,
 
        INIT_LIST_HEAD(&priv->pgdir_list);
        mutex_init(&priv->pgdir_mutex);
+       spin_lock_init(&priv->cmd.context_lock);
 
        INIT_LIST_HEAD(&priv->bf_list);
        mutex_init(&priv->bf_mutex);