net/mlx5: Replace global mlx5_intf_lock with HCA devcom component lock

mlx5_intf_lock is used to sync between LAG changes and its slaves
mlx5 core dev aux devices changes, which means every time mlx5 core
dev add/remove aux devices, mlx5 is taking this global lock, even if
LAG functionality isn't supported over the core dev.
This cause a bottleneck when probing VFs/SFs in parallel.

Hence, replace mlx5_intf_lock with HCA devcom component lock, or no
lock if LAG functionality isn't supported.

Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/dev.c

@@ -38,8 +38,6 @@
 #include "devlink.h"
 #include "lag/lag.h"
 
-/* intf dev list mutex */
-static DEFINE_MUTEX(mlx5_intf_mutex);
 static DEFINE_IDA(mlx5_adev_ida);
 
 static bool is_eth_rep_supported(struct mlx5_core_dev *dev)
@@ -337,9 +335,9 @@ static void del_adev(struct auxiliary_device *adev)
 
 void mlx5_dev_set_lightweight(struct mlx5_core_dev *dev)
 {
-	mutex_lock(&mlx5_intf_mutex);
+	mlx5_devcom_comp_lock(dev->priv.hca_devcom_comp);
 	dev->priv.flags |= MLX5_PRIV_FLAGS_DISABLE_ALL_ADEV;
-	mutex_unlock(&mlx5_intf_mutex);
+	mlx5_devcom_comp_unlock(dev->priv.hca_devcom_comp);
 }
 
 bool mlx5_dev_is_lightweight(struct mlx5_core_dev *dev)
@@ -355,7 +353,7 @@ int mlx5_attach_device(struct mlx5_core_dev *dev)
 	int ret = 0, i;
 
 	devl_assert_locked(priv_to_devlink(dev));
-	mutex_lock(&mlx5_intf_mutex);
+	mlx5_devcom_comp_lock(dev->priv.hca_devcom_comp);
 	priv->flags &= ~MLX5_PRIV_FLAGS_DETACH;
 	for (i = 0; i < ARRAY_SIZE(mlx5_adev_devices); i++) {
 		if (!priv->adev[i]) {
@@ -400,7 +398,7 @@ int mlx5_attach_device(struct mlx5_core_dev *dev)
 			break;
 		}
 	}
-	mutex_unlock(&mlx5_intf_mutex);
+	mlx5_devcom_comp_unlock(dev->priv.hca_devcom_comp);
 	return ret;
 }
 
@@ -413,7 +411,7 @@ void mlx5_detach_device(struct mlx5_core_dev *dev, bool suspend)
 	int i;
 
 	devl_assert_locked(priv_to_devlink(dev));
-	mutex_lock(&mlx5_intf_mutex);
+	mlx5_devcom_comp_lock(dev->priv.hca_devcom_comp);
 	for (i = ARRAY_SIZE(mlx5_adev_devices) - 1; i >= 0; i--) {
 		if (!priv->adev[i])
 			continue;
@@ -443,7 +441,7 @@ void mlx5_detach_device(struct mlx5_core_dev *dev, bool suspend)
 		priv->adev[i] = NULL;
 	}
 	priv->flags |= MLX5_PRIV_FLAGS_DETACH;
-	mutex_unlock(&mlx5_intf_mutex);
+	mlx5_devcom_comp_unlock(dev->priv.hca_devcom_comp);
 }
 
 int mlx5_register_device(struct mlx5_core_dev *dev)
@@ -451,10 +449,10 @@ int mlx5_register_device(struct mlx5_core_dev *dev)
 	int ret;
 
 	devl_assert_locked(priv_to_devlink(dev));
-	mutex_lock(&mlx5_intf_mutex);
+	mlx5_devcom_comp_lock(dev->priv.hca_devcom_comp);
 	dev->priv.flags &= ~MLX5_PRIV_FLAGS_DISABLE_ALL_ADEV;
 	ret = mlx5_rescan_drivers_locked(dev);
-	mutex_unlock(&mlx5_intf_mutex);
+	mlx5_devcom_comp_unlock(dev->priv.hca_devcom_comp);
 	if (ret)
 		mlx5_unregister_device(dev);
 
@@ -464,10 +462,10 @@ int mlx5_register_device(struct mlx5_core_dev *dev)
 void mlx5_unregister_device(struct mlx5_core_dev *dev)
 {
 	devl_assert_locked(priv_to_devlink(dev));
-	mutex_lock(&mlx5_intf_mutex);
+	mlx5_devcom_comp_lock(dev->priv.hca_devcom_comp);
 	dev->priv.flags = MLX5_PRIV_FLAGS_DISABLE_ALL_ADEV;
 	mlx5_rescan_drivers_locked(dev);
-	mutex_unlock(&mlx5_intf_mutex);
+	mlx5_devcom_comp_unlock(dev->priv.hca_devcom_comp);
 }
 
 static int add_drivers(struct mlx5_core_dev *dev)
@@ -545,7 +543,6 @@ int mlx5_rescan_drivers_locked(struct mlx5_core_dev *dev)
 {
 	struct mlx5_priv *priv = &dev->priv;
 
-	lockdep_assert_held(&mlx5_intf_mutex);
 	if (priv->flags & MLX5_PRIV_FLAGS_DETACH)
 		return 0;
 
@@ -565,17 +562,3 @@ 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);
 }
-
-void mlx5_dev_list_lock(void)
-{
-	mutex_lock(&mlx5_intf_mutex);
-}
-void mlx5_dev_list_unlock(void)
-{
-	mutex_unlock(&mlx5_intf_mutex);
-}
-
-int mlx5_dev_list_trylock(void)
-{
-	return mutex_trylock(&mlx5_intf_mutex);
-}

drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c

@@ -943,6 +943,26 @@ static void mlx5_do_bond(struct mlx5_lag *ldev)
 	}
 }
 
+/* The last mdev to unregister will destroy the workqueue before removing the
+ * devcom component, and as all the mdevs use the same devcom component we are
+ * guaranteed that the devcom is valid while the calling work is running.
+ */
+struct mlx5_devcom_comp_dev *mlx5_lag_get_devcom_comp(struct mlx5_lag *ldev)
+{
+	struct mlx5_devcom_comp_dev *devcom = NULL;
+	int i;
+
+	mutex_lock(&ldev->lock);
+	for (i = 0; i < ldev->ports; i++) {
+		if (ldev->pf[i].dev) {
+			devcom = ldev->pf[i].dev->priv.hca_devcom_comp;
+			break;
+		}
+	}
+	mutex_unlock(&ldev->lock);
+	return devcom;
+}
+
 static void mlx5_queue_bond_work(struct mlx5_lag *ldev, unsigned long delay)
 {
 	queue_delayed_work(ldev->wq, &ldev->bond_work, delay);
@@ -953,9 +973,14 @@ static void mlx5_do_bond_work(struct work_struct *work)
 	struct delayed_work *delayed_work = to_delayed_work(work);
 	struct mlx5_lag *ldev = container_of(delayed_work, struct mlx5_lag,
 					     bond_work);
+	struct mlx5_devcom_comp_dev *devcom;
 	int status;
 
-	status = mlx5_dev_list_trylock();
+	devcom = mlx5_lag_get_devcom_comp(ldev);
+	if (!devcom)
+		return;
+
+	status = mlx5_devcom_comp_trylock(devcom);
 	if (!status) {
 		mlx5_queue_bond_work(ldev, HZ);
 		return;
@@ -964,14 +989,14 @@ static void mlx5_do_bond_work(struct work_struct *work)
 	mutex_lock(&ldev->lock);
 	if (ldev->mode_changes_in_progress) {
 		mutex_unlock(&ldev->lock);
-		mlx5_dev_list_unlock();
+		mlx5_devcom_comp_unlock(devcom);
 		mlx5_queue_bond_work(ldev, HZ);
 		return;
 	}
 
 	mlx5_do_bond(ldev);
 	mutex_unlock(&ldev->lock);
-	mlx5_dev_list_unlock();
+	mlx5_devcom_comp_unlock(devcom);
 }
 
 static int mlx5_handle_changeupper_event(struct mlx5_lag *ldev,
@@ -1435,7 +1460,7 @@ void mlx5_lag_disable_change(struct mlx5_core_dev *dev)
 	if (!ldev)
 		return;
 
-	mlx5_dev_list_lock();
+	mlx5_devcom_comp_lock(dev->priv.hca_devcom_comp);
 	mutex_lock(&ldev->lock);
 
 	ldev->mode_changes_in_progress++;
@@ -1443,7 +1468,7 @@ void mlx5_lag_disable_change(struct mlx5_core_dev *dev)
 		mlx5_disable_lag(ldev);
 
 	mutex_unlock(&ldev->lock);
-	mlx5_dev_list_unlock();
+	mlx5_devcom_comp_unlock(dev->priv.hca_devcom_comp);
 }
 
 void mlx5_lag_enable_change(struct mlx5_core_dev *dev)

drivers/net/ethernet/mellanox/mlx5/core/lag/lag.h

@@ -112,6 +112,7 @@ void mlx5_disable_lag(struct mlx5_lag *ldev);
 void mlx5_lag_remove_devices(struct mlx5_lag *ldev);
 int mlx5_deactivate_lag(struct mlx5_lag *ldev);
 void mlx5_lag_add_devices(struct mlx5_lag *ldev);
+struct mlx5_devcom_comp_dev *mlx5_lag_get_devcom_comp(struct mlx5_lag *ldev);
 
 static inline bool mlx5_lag_is_supported(struct mlx5_core_dev *dev)
 {

drivers/net/ethernet/mellanox/mlx5/core/lag/mpesw.c

@@ -129,9 +129,14 @@ static void disable_mpesw(struct mlx5_lag *ldev)
 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_devcom_comp_dev *devcom;
 	struct mlx5_lag *ldev = mpesww->lag;
 
-	mlx5_dev_list_lock();
+	devcom = mlx5_lag_get_devcom_comp(ldev);
+	if (!devcom)
+		return;
+
+	mlx5_devcom_comp_lock(devcom);
 	mutex_lock(&ldev->lock);
 	if (ldev->mode_changes_in_progress) {
 		mpesww->result = -EAGAIN;
@@ -144,7 +149,7 @@ static void mlx5_mpesw_work(struct work_struct *work)
 		disable_mpesw(ldev);
 unlock:
 	mutex_unlock(&ldev->lock);
-	mlx5_dev_list_unlock();
+	mlx5_devcom_comp_unlock(devcom);
 	complete(&mpesww->comp);
 }
 

drivers/net/ethernet/mellanox/mlx5/core/lib/devcom.c

@@ -401,3 +401,10 @@ void mlx5_devcom_comp_unlock(struct mlx5_devcom_comp_dev *devcom)
 		return;
 	up_write(&devcom->comp->sem);
 }
+
+int mlx5_devcom_comp_trylock(struct mlx5_devcom_comp_dev *devcom)
+{
+	if (IS_ERR_OR_NULL(devcom))
+		return 0;
+	return down_write_trylock(&devcom->comp->sem);
+}

drivers/net/ethernet/mellanox/mlx5/core/lib/devcom.h

@@ -55,5 +55,6 @@ void *mlx5_devcom_get_next_peer_data_rcu(struct mlx5_devcom_comp_dev *devcom,
 
 void mlx5_devcom_comp_lock(struct mlx5_devcom_comp_dev *devcom);
 void mlx5_devcom_comp_unlock(struct mlx5_devcom_comp_dev *devcom);
+int mlx5_devcom_comp_trylock(struct mlx5_devcom_comp_dev *devcom);
 
 #endif /* __LIB_MLX5_DEVCOM_H__ */

drivers/net/ethernet/mellanox/mlx5/core/mlx5_core.h

@@ -41,6 +41,7 @@
 #include <linux/mlx5/cq.h>
 #include <linux/mlx5/fs.h>
 #include <linux/mlx5/driver.h>
+#include "lib/devcom.h"
 
 extern uint mlx5_core_debug_mask;
 
@@ -266,9 +267,6 @@ int mlx5_register_device(struct mlx5_core_dev *dev);
 void mlx5_unregister_device(struct mlx5_core_dev *dev);
 void mlx5_dev_set_lightweight(struct mlx5_core_dev *dev);
 bool mlx5_dev_is_lightweight(struct mlx5_core_dev *dev);
-void mlx5_dev_list_lock(void);
-void mlx5_dev_list_unlock(void);
-int mlx5_dev_list_trylock(void);
 
 void mlx5_fw_reporters_create(struct mlx5_core_dev *dev);
 int mlx5_query_mtpps(struct mlx5_core_dev *dev, u32 *mtpps, u32 mtpps_size);
@@ -307,9 +305,9 @@ static inline int mlx5_rescan_drivers(struct mlx5_core_dev *dev)
 {
 	int ret;
 
-	mlx5_dev_list_lock();
+	mlx5_devcom_comp_lock(dev->priv.hca_devcom_comp);
 	ret = mlx5_rescan_drivers_locked(dev);
-	mlx5_dev_list_unlock();
+	mlx5_devcom_comp_unlock(dev->priv.hca_devcom_comp);
 	return ret;
 }