mlx5_core: Fix possible race between mr tree insert/delete

In mlx5_core_destroy_mkey(), we must first remove the mr from the
radix tree and then destroy it.  Otherwise we might hit a race if the
key was reallocated and we attempted to insert it to the radix tree.

Also handle radix tree insert/delete failures.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-by: Eli Cohen <elic@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 15 insertions, 4 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/mr.c b/drivers/net/ethernet/mellanox/mlx5/core/mr.c
index ba0401d4af50..184c3615f479 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/mr.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/mr.c
@@ -94,6 +94,11 @@ int mlx5_core_create_mkey(struct mlx5_core_dev *dev, struct mlx5_core_mr *mr,
         write_lock_irq(&table->lock);
         err = radix_tree_insert(&table->tree, mlx5_base_mkey(mr->key), mr);
         write_unlock_irq(&table->lock);
+        if (err) {
+                mlx5_core_warn(dev, "failed radix tree insert of mr 0x%x, %d\n",
+                               mlx5_base_mkey(mr->key), err);
+                mlx5_core_destroy_mkey(dev, mr);
+        }
 
         return err;
 }
@@ -104,12 +109,22 @@ int mlx5_core_destroy_mkey(struct mlx5_core_dev *dev, struct mlx5_core_mr *mr)
         struct mlx5_mr_table *table = &dev->priv.mr_table;
         struct mlx5_destroy_mkey_mbox_in in;
         struct mlx5_destroy_mkey_mbox_out out;
+        struct mlx5_core_mr *deleted_mr;
         unsigned long flags;
         int err;
 
         memset(&in, 0, sizeof(in));
         memset(&out, 0, sizeof(out));
 
+        write_lock_irqsave(&table->lock, flags);
+        deleted_mr = radix_tree_delete(&table->tree, mlx5_base_mkey(mr->key));
+        write_unlock_irqrestore(&table->lock, flags);
+        if (!deleted_mr) {
+                mlx5_core_warn(dev, "failed radix tree delete of mr 0x%x\n",
+                               mlx5_base_mkey(mr->key));
+                return -ENOENT;
+        }
+
         in.hdr.opcode = cpu_to_be16(MLX5_CMD_OP_DESTROY_MKEY);
         in.mkey = cpu_to_be32(mlx5_mkey_to_idx(mr->key));
         err = mlx5_cmd_exec(dev, &in, sizeof(in), &out, sizeof(out));
@@ -119,10 +134,6 @@ int mlx5_core_destroy_mkey(struct mlx5_core_dev *dev, struct mlx5_core_mr *mr)
         if (out.hdr.status)
                 return mlx5_cmd_status_to_err(&out.hdr);
 
-        write_lock_irqsave(&table->lock, flags);
-        radix_tree_delete(&table->tree, mlx5_base_mkey(mr->key));
-        write_unlock_irqrestore(&table->lock, flags);
-
         return err;
 }
 EXPORT_SYMBOL(mlx5_core_destroy_mkey);