[PATCH 3/3] maple_tree: assert retrieving new value on a tree with only root node

[Liam R. Howlett]

* Wei Yang <richard.weiyang at gmail.com> [250207 20:26]:
> Original code may get a stall value when overwriting the whole range on a
                          ^^^^^- stale value.  I thought you were saying
			  it was stalling which did not make sense.

> maple tree with only root node. The reason is we didn't set the only
> root node dead during destroy.
> 
> Add a test case to verify this is not recreated.
> 
> Signed-off-by: Wei Yang <richard.weiyang at gmail.com>
> CC: Liam R. Howlett <Liam.Howlett at Oracle.com>
> ---
>  tools/testing/radix-tree/maple.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/tools/testing/radix-tree/maple.c b/tools/testing/radix-tree/maple.c
> index bc30050227fd..1e293e4d856d 100644
> --- a/tools/testing/radix-tree/maple.c
> +++ b/tools/testing/radix-tree/maple.c
> @@ -35256,6 +35256,30 @@ static noinline void __init check_rcu_simulated(struct maple_tree *mt)
>  	MT_BUG_ON(mt, mas_prev(&mas_reader, 0) != xa_mk_value(val));
>  	rcu_read_unlock();
>  
> +	/* Clear out tree & create one with only root node */
> +	mas_lock(&mas_writer);
> +	mas_set_range(&mas_writer, 0, ULONG_MAX);
> +	mas_store_gfp(&mas_writer, NULL, GFP_KERNEL);
> +	mas_set_range(&mas_writer, 0, 0);
> +	for (i = 0; i <= 5; i++) {
> +		mas_writer.index = i * 10;
> +		mas_writer.last = i * 10 + 5;
> +		mas_store_gfp(&mas_writer, xa_mk_value(i), GFP_KERNEL);
> +	}
> +	mas_unlock(&mas_writer);
> +	target = 10;
> +	mas_set_range(&mas_reader, target, target);
> +	rcu_read_lock();
> +	MT_BUG_ON(mt, mas_walk(&mas_reader) != xa_mk_value(target/10));
> +
> +	/* Overwrite the whole range */
> +	mas_lock(&mas_writer);
> +	mas_set_range(&mas_writer, 0, ULONG_MAX);
> +	mas_store_gfp(&mas_writer, xa_mk_value(val), GFP_KERNEL);
> +	mas_unlock(&mas_writer);
> +	MT_BUG_ON(mt, mas_walk(&mas_reader) != xa_mk_value(val));
> +	rcu_read_unlock();
> +
>  	rcu_unregister_thread();
>  }
>  
> -- 
> 2.34.1
>