net/mlx5: Convert mkey_table to XArray

The lock protecting the data structure does not need to be an rwlock.  The
only read access to the lock is in an error path, and if that's limiting
your scalability, you have bigger performance problems.

Eliminate mlx5_mkey_table in favour of using the xarray directly.
reg_mr_callback must use GFP_ATOMIC for allocating XArray nodes as it may
be called in interrupt context.

This also fixes a minor bug where SRCU locking was being used on the radix
tree read side, when RCU was needed too.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

1 files changed, 11 insertions, 16 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/mr.c b/drivers/net/ethernet/mellanox/mlx5/core/mr.c
index ea744d8466ea..9231b39d18b2 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/mr.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/mr.c
@@ -38,15 +38,12 @@
 
 void mlx5_init_mkey_table(struct mlx5_core_dev *dev)
 {
-	struct mlx5_mkey_table *table = &dev->priv.mkey_table;
-
-	memset(table, 0, sizeof(*table));
-	rwlock_init(&table->lock);
-	INIT_RADIX_TREE(&table->tree, GFP_ATOMIC);
+	xa_init_flags(&dev->priv.mkey_table, XA_FLAGS_LOCK_IRQ);
 }
 
 void mlx5_cleanup_mkey_table(struct mlx5_core_dev *dev)
 {
+	WARN_ON(!xa_empty(&dev->priv.mkey_table));
 }
 
 int mlx5_core_create_mkey_cb(struct mlx5_core_dev *dev,
@@ -56,8 +53,8 @@ int mlx5_core_create_mkey_cb(struct mlx5_core_dev *dev,
 			     mlx5_async_cbk_t callback,
 			     struct mlx5_async_work *context)
 {
-	struct mlx5_mkey_table *table = &dev->priv.mkey_table;
 	u32 lout[MLX5_ST_SZ_DW(create_mkey_out)] = {0};
+	struct xarray *mkeys = &dev->priv.mkey_table;
 	u32 mkey_index;
 	void *mkc;
 	int err;
@@ -88,12 +85,10 @@ int mlx5_core_create_mkey_cb(struct mlx5_core_dev *dev,
 	mlx5_core_dbg(dev, "out 0x%x, key 0x%x, mkey 0x%x\n",
 		      mkey_index, key, mkey->key);
 
-	/* connect to mkey tree */
-	write_lock_irq(&table->lock);
-	err = radix_tree_insert(&table->tree, mlx5_base_mkey(mkey->key), mkey);
-	write_unlock_irq(&table->lock);
+	err = xa_err(xa_store_irq(mkeys, mlx5_base_mkey(mkey->key), mkey,
+				  GFP_KERNEL));
 	if (err) {
-		mlx5_core_warn(dev, "failed radix tree insert of mkey 0x%x, %d\n",
+		mlx5_core_warn(dev, "failed xarray insert of mkey 0x%x, %d\n",
 			       mlx5_base_mkey(mkey->key), err);
 		mlx5_core_destroy_mkey(dev, mkey);
 	}
@@ -114,17 +109,17 @@ EXPORT_SYMBOL(mlx5_core_create_mkey);
 int mlx5_core_destroy_mkey(struct mlx5_core_dev *dev,
 			   struct mlx5_core_mkey *mkey)
 {
-	struct mlx5_mkey_table *table = &dev->priv.mkey_table;
 	u32 out[MLX5_ST_SZ_DW(destroy_mkey_out)] = {0};
 	u32 in[MLX5_ST_SZ_DW(destroy_mkey_in)]   = {0};
+	struct xarray *mkeys = &dev->priv.mkey_table;
 	struct mlx5_core_mkey *deleted_mkey;
 	unsigned long flags;
 
-	write_lock_irqsave(&table->lock, flags);
-	deleted_mkey = radix_tree_delete(&table->tree, mlx5_base_mkey(mkey->key));
-	write_unlock_irqrestore(&table->lock, flags);
+	xa_lock_irqsave(mkeys, flags);
+	deleted_mkey = __xa_erase(mkeys, mlx5_base_mkey(mkey->key));
+	xa_unlock_irqrestore(mkeys, flags);
 	if (!deleted_mkey) {
-		mlx5_core_dbg(dev, "failed radix tree delete of mkey 0x%x\n",
+		mlx5_core_dbg(dev, "failed xarray delete of mkey 0x%x\n",
 			      mlx5_base_mkey(mkey->key));
 		return -ENOENT;
 	}