mlx4_core: Fix crash on uninitialized priv->cmd.slave_sem

On an SR-IOV master device, __mlx4_init_one() calls mlx4_init_hca()
before mlx4_multi_func_init().  However, for unlucky configurations,
mlx4_init_hca() might call mlx4_SENSE_PORT() (via mlx4_dev_cap()), and
that calls mlx4_cmd_imm() with MLX4_CMD_WRAPPED set.

However, on a multifunction device with MLX4_CMD_WRAPPED, __mlx4_cmd()
calls into mlx4_slave_cmd(), and that immediately tries to do

	down(&priv->cmd.slave_sem);

but priv->cmd.slave_sem isn't initialized until mlx4_multi_func_init()
(which we haven't called yet).  The next thing it tries to do is access
priv->mfunc.vhcr, but that hasn't been allocated yet.

Fix this by moving the initialization of slave_sem and vhcr up into
mlx4_cmd_init(). Also, since slave_sem is really just being used as a
mutex, convert it into a slave_cmd_mutex.

Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx4/main.c b/drivers/net/ethernet/mellanox/mlx4/main.c
index 296288c7cb3..1e9f816a94d 100644
--- a/drivers/net/ethernet/mellanox/mlx4/main.c
+++ b/drivers/net/ethernet/mellanox/mlx4/main.c
@@ -1159,10 +1159,10 @@ static void mlx4_slave_exit(struct mlx4_dev *dev)
 {
 	struct mlx4_priv *priv = mlx4_priv(dev);
 
-	down(&priv->cmd.slave_sem);
+	mutex_lock(&priv->cmd.slave_cmd_mutex);
 	if (mlx4_comm_cmd(dev, MLX4_COMM_CMD_RESET, 0, MLX4_COMM_TIME))
 		mlx4_warn(dev, "Failed to close slave function.\n");
-	up(&priv->cmd.slave_sem);
+	mutex_unlock(&priv->cmd.slave_cmd_mutex);
 }
 
 static int map_bf_area(struct mlx4_dev *dev)
@@ -1214,7 +1214,7 @@ static int mlx4_init_slave(struct mlx4_dev *dev)
 	u32 slave_read;
 	u32 cmd_channel_ver;
 
-	down(&priv->cmd.slave_sem);
+	mutex_lock(&priv->cmd.slave_cmd_mutex);
 	priv->cmd.max_cmds = 1;
 	mlx4_warn(dev, "Sending reset\n");
 	ret_from_reset = mlx4_comm_cmd(dev, MLX4_COMM_CMD_RESET, 0,
@@ -1263,12 +1263,13 @@ static int mlx4_init_slave(struct mlx4_dev *dev)
 		goto err;
 	if (mlx4_comm_cmd(dev, MLX4_COMM_CMD_VHCR_EN, dma, MLX4_COMM_TIME))
 		goto err;
-	up(&priv->cmd.slave_sem);
+
+	mutex_unlock(&priv->cmd.slave_cmd_mutex);
 	return 0;
 
 err:
 	mlx4_comm_cmd(dev, MLX4_COMM_CMD_RESET, 0, 0);
-	up(&priv->cmd.slave_sem);
+	mutex_unlock(&priv->cmd.slave_cmd_mutex);
 	return -EIO;
 }