Subject: Re: [net-next V2 04/15] net/mlx5: Refactor LAG peer device lookout bus logic to mlx5 devcom

From: Saeed Mahameed <[email-masked]>
Date: Thu, 12 Oct 2023 14:46:49 -0700

On 12 Oct 14:26, Jacob Keller wrote:
>
>
>On 10/12/2023 12:27 PM, Saeed Mahameed wrote:
>> From: Shay Drory <[email-masked]>
>>
>> LAG peer device lookout bus logic required the usage of global lock,
>> mlx5_intf_mutex.
>> As part of the effort to remove this global lock, refactor LAG peer
>> device lookout to use mlx5 devcom layer.
>>
>> Signed-off-by: Shay Drory <[email-masked]>
>> Reviewed-by: Mark Bloch <[email-masked]>
>> Signed-off-by: Saeed Mahameed <[email-masked]>
>> ---
>>  drivers/net/ethernet/mellanox/mlx5/core/dev.c | 68 -------------------
>>  .../net/ethernet/mellanox/mlx5/core/lag/lag.c | 12 ++--
>>  .../ethernet/mellanox/mlx5/core/lib/devcom.c  | 14 ++++
>>  .../ethernet/mellanox/mlx5/core/lib/devcom.h  |  4 ++
>>  .../net/ethernet/mellanox/mlx5/core/main.c    | 25 +++++++
>>  .../ethernet/mellanox/mlx5/core/mlx5_core.h   |  1 -
>>  include/linux/mlx5/driver.h                   |  1 +
>>  7 files changed, 52 insertions(+), 73 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/dev.c b/drivers/net/ethernet/mellanox/mlx5/core/dev.c
>> index 1fc03480c2ff..6e3a8c22881f 100644
>> --- a/drivers/net/ethernet/mellanox/mlx5/core/dev.c
>> +++ b/drivers/net/ethernet/mellanox/mlx5/core/dev.c
>> @@ -566,74 +566,6 @@ bool mlx5_same_hw_devs(struct mlx5_core_dev *dev, struct mlx5_core_dev *peer_dev
>>  	return (fsystem_guid && psystem_guid && fsystem_guid == psystem_guid);
>>  }
>>
>> -static u32 mlx5_gen_pci_id(const struct mlx5_core_dev *dev)
>> -{
>> -	return (u32)((pci_domain_nr(dev->pdev->bus) << 16) |
>> -		     (dev->pdev->bus->number << 8) |
>> -		     PCI_SLOT(dev->pdev->devfn));
>> -}
>> -
>> -static int _next_phys_dev(struct mlx5_core_dev *mdev,
>> -			  const struct mlx5_core_dev *curr)
>> -{
>> -	if (!mlx5_core_is_pf(mdev))
>> -		return 0;
>> -
>> -	if (mdev == curr)
>> -		return 0;
>> -
>> -	if (!mlx5_same_hw_devs(mdev, (struct mlx5_core_dev *)curr) &&
>> -	    mlx5_gen_pci_id(mdev) != mlx5_gen_pci_id(curr))
>> -		return 0;
>> -
>> -	return 1;
>> -}
>> -
>> -static void *pci_get_other_drvdata(struct device *this, struct device *other)
>> -{
>> -	if (this->driver != other->driver)
>> -		return NULL;
>> -
>> -	return pci_get_drvdata(to_pci_dev(other));
>> -}
>> -
>> -static int next_phys_dev_lag(struct device *dev, const void *data)
>> -{
>> -	struct mlx5_core_dev *mdev, *this = (struct mlx5_core_dev *)data;
>> -
>> -	mdev = pci_get_other_drvdata(this->device, dev);
>> -	if (!mdev)
>> -		return 0;
>> -
>> -	if (!mlx5_lag_is_supported(mdev))
>> -		return 0;
>> -
>> -	return _next_phys_dev(mdev, data);
>> -}
>> -
>> -static struct mlx5_core_dev *mlx5_get_next_dev(struct mlx5_core_dev *dev,
>> -					       int (*match)(struct device *dev, const void *data))
>> -{
>> -	struct device *next;
>> -
>> -	if (!mlx5_core_is_pf(dev))
>> -		return NULL;
>> -
>> -	next = bus_find_device(&pci_bus_type, NULL, dev, match);
>> -	if (!next)
>> -		return NULL;
>> -
>> -	put_device(next);
>> -	return pci_get_drvdata(to_pci_dev(next));
>> -}
>> -
>> -/* Must be called with intf_mutex held */
>> -struct mlx5_core_dev *mlx5_get_next_phys_dev_lag(struct mlx5_core_dev *dev)
>> -{
>> -	lockdep_assert_held(&mlx5_intf_mutex);
>
>The old flow had a lockdep_assert_held
>
>> -	return mlx5_get_next_dev(dev, &next_phys_dev_lag);
>> -}
>> -
>>  void mlx5_dev_list_lock(void)
>>  {
>>  	mutex_lock(&mlx5_intf_mutex);
>> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c
>> index af3fac090b82..f0b57f97739f 100644
>> --- a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c
>> +++ b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c
>> @@ -1212,13 +1212,14 @@ static void mlx5_ldev_remove_mdev(struct mlx5_lag *ldev,
>>  	dev->priv.lag = NULL;
>>  }
>>
>> -/* Must be called with intf_mutex held */
>> +/* Must be called with HCA devcom component lock held */
>>  static int __mlx5_lag_dev_add_mdev(struct mlx5_core_dev *dev)
>>  {
>> +	struct mlx5_devcom_comp_dev *pos = NULL;
>>  	struct mlx5_lag *ldev = NULL;
>>  	struct mlx5_core_dev *tmp_dev;
>>
>> -	tmp_dev = mlx5_get_next_phys_dev_lag(dev);
>> +	tmp_dev = mlx5_devcom_get_next_peer_data(dev->priv.hca_devcom_comp, &pos);
>>  	if (tmp_dev)
>>  		ldev = mlx5_lag_dev(tmp_dev);
>>
>
>But you didn't bother to add one here? Does
>mlx5_devcom_get_next_peer_data already do that?
>

The global mutex isn't required anymore after this refactoring,
and devcom has own locking and sync mechanism.

>Not a big deal either way to me.
>
>Reviewed-by: Jacob Keller <[email-masked]>