Re: [PATCH v2 1/1] util: Make some iova_tree parameters const

[Paolo Bonzini <pbonzini@redhat.com>]

On 13/10/21 20:27, Eugenio Pérez wrote:
> As qemu guidelines:
> Unless a pointer is used to modify the pointed-to storage, give it the
> "const" attribute.
> 
> In the particular case of iova_tree_find it allows to enforce what is
> requested by its comment, since the compiler would shout in case of
> modifying or freeing the const-qualified returned pointer.
> 
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> Acked-by: Peter Xu <peterx@redhat.com>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>   include/qemu/iova-tree.h |  8 ++++----
>   hw/i386/intel_iommu.c    |  2 +-
>   util/iova-tree.c         | 12 ++++++------
>   3 files changed, 11 insertions(+), 11 deletions(-)
> 
> diff --git a/include/qemu/iova-tree.h b/include/qemu/iova-tree.h
> index b66cf93c4b..8249edd764 100644
> --- a/include/qemu/iova-tree.h
> +++ b/include/qemu/iova-tree.h
> @@ -59,7 +59,7 @@ IOVATree *iova_tree_new(void);
>    *
>    * Return: 0 if succeeded, or <0 if error.
>    */
> -int iova_tree_insert(IOVATree *tree, DMAMap *map);
> +int iova_tree_insert(IOVATree *tree, const DMAMap *map);
>   
>   /**
>    * iova_tree_remove:
> @@ -74,7 +74,7 @@ int iova_tree_insert(IOVATree *tree, DMAMap *map);
>    *
>    * Return: 0 if succeeded, or <0 if error.
>    */
> -int iova_tree_remove(IOVATree *tree, DMAMap *map);
> +int iova_tree_remove(IOVATree *tree, const DMAMap *map);
>   
>   /**
>    * iova_tree_find:
> @@ -92,7 +92,7 @@ int iova_tree_remove(IOVATree *tree, DMAMap *map);
>    * user is responsible to make sure the pointer is valid (say, no
>    * concurrent deletion in progress).
>    */
> -DMAMap *iova_tree_find(IOVATree *tree, DMAMap *map);
> +const DMAMap *iova_tree_find(const IOVATree *tree, const DMAMap *map);
>   
>   /**
>    * iova_tree_find_address:
> @@ -105,7 +105,7 @@ DMAMap *iova_tree_find(IOVATree *tree, DMAMap *map);
>    *
>    * Return: same as iova_tree_find().
>    */
> -DMAMap *iova_tree_find_address(IOVATree *tree, hwaddr iova);
> +const DMAMap *iova_tree_find_address(const IOVATree *tree, hwaddr iova);
>   
>   /**
>    * iova_tree_foreach:
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index 75f075547f..33a8af9191 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -1105,7 +1105,7 @@ static int vtd_page_walk_one(IOMMUTLBEvent *event, vtd_page_walk_info *info)
>           .translated_addr = entry->translated_addr,
>           .perm = entry->perm,
>       };
> -    DMAMap *mapped = iova_tree_find(as->iova_tree, &target);
> +    const DMAMap *mapped = iova_tree_find(as->iova_tree, &target);
>   
>       if (event->type == IOMMU_NOTIFIER_UNMAP && !info->notify_unmap) {
>           trace_vtd_page_walk_one_skip_unmap(entry->iova, entry->addr_mask);
> diff --git a/util/iova-tree.c b/util/iova-tree.c
> index 7990692cbd..23ea35b7a4 100644
> --- a/util/iova-tree.c
> +++ b/util/iova-tree.c
> @@ -42,14 +42,14 @@ IOVATree *iova_tree_new(void)
>       return iova_tree;
>   }
>   
> -DMAMap *iova_tree_find(IOVATree *tree, DMAMap *map)
> +const DMAMap *iova_tree_find(const IOVATree *tree, const DMAMap *map)
>   {
>       return g_tree_lookup(tree->tree, map);
>   }
>   
> -DMAMap *iova_tree_find_address(IOVATree *tree, hwaddr iova)
> +const DMAMap *iova_tree_find_address(const IOVATree *tree, hwaddr iova)
>   {
> -    DMAMap map = { .iova = iova, .size = 0 };
> +    const DMAMap map = { .iova = iova, .size = 0 };
>   
>       return iova_tree_find(tree, &map);
>   }
> @@ -60,7 +60,7 @@ static inline void iova_tree_insert_internal(GTree *gtree, DMAMap *range)
>       g_tree_insert(gtree, range, range);
>   }
>   
> -int iova_tree_insert(IOVATree *tree, DMAMap *map)
> +int iova_tree_insert(IOVATree *tree, const DMAMap *map)
>   {
>       DMAMap *new;
>   
> @@ -96,9 +96,9 @@ void iova_tree_foreach(IOVATree *tree, iova_tree_iterator iterator)
>       g_tree_foreach(tree->tree, iova_tree_traverse, iterator);
>   }
>   
> -int iova_tree_remove(IOVATree *tree, DMAMap *map)
> +int iova_tree_remove(IOVATree *tree, const DMAMap *map)
>   {
> -    DMAMap *overlap;
> +    const DMAMap *overlap;
>   
>       while ((overlap = iova_tree_find(tree, map))) {
>           g_tree_remove(tree->tree, overlap);
> 

Queued, thanks.

Paolo