Re: [PATCH 3/7] util: make a copy of iova_tree_remove_parameter

[Jason Wang <jasowang@redhat.com>]

在 2022/8/20 00:53, Eugenio Pérez 写道:
> It's convenient to call iova_tree_remove from a map returned from
> iova_tree_find or iova_tree_find_iova.


The looks like a hint of the defect of current API.


>   With the current code this is not
> possible, since we will free it, and then we will try to search for it
> again.
>
> Fix it making a copy of the argument. Not applying a fixes tag, since
> there is no use like that at the moment.
>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
>   util/iova-tree.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/util/iova-tree.c b/util/iova-tree.c
> index fee530a579..713e3edd7b 100644
> --- a/util/iova-tree.c
> +++ b/util/iova-tree.c
> @@ -166,9 +166,11 @@ void iova_tree_foreach(IOVATree *tree, iova_tree_iterator iterator)
>   
>   void iova_tree_remove(IOVATree *tree, const DMAMap *map)
>   {
> +    /* Just in case caller is calling iova_tree_remove from a result of find */
> +    const DMAMap needle = *map;


Then let's simply make iova_tree_remove() accept const DMAMap instead of 
the pointer to it.


>       const DMAMap *overlap;
>   
> -    while ((overlap = iova_tree_find(tree, map))) {
> +    while ((overlap = iova_tree_find(tree, &needle))) {
>           g_tree_remove(tree->tree, overlap);
>       }


So we had following in iova_tree_insert():

     /* We don't allow to insert range that overlaps with existings */
     if (iova_tree_find(tree, map)) {
         return IOVA_ERR_OVERLAP;
     }

I wonder how overlap can happen?

Thanks



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