[PATCH 0/1] util: Make some iova_tree functions parameters const

[PATCH 0/1] util: Make some iova_tree functions parameters const

[Eugenio Pérez]

Some guidelines misses I found while working on Shadow Virtqueue, that
uses these functions at this moment.

Eugenio Pérez (1):
  util: Make some iova_tree parameters const

 include/qemu/iova-tree.h |  8 ++++----
 hw/i386/intel_iommu.c    |  2 +-
 util/iova-tree.c         | 10 +++++-----
 3 files changed, 10 insertions(+), 10 deletions(-)

-- 
2.27.0

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

[Eugenio Pérez]

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>
---
 include/qemu/iova-tree.h |  8 ++++----
 hw/i386/intel_iommu.c    |  2 +-
 util/iova-tree.c         | 10 +++++-----
 3 files changed, 10 insertions(+), 10 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..8ca6af21cf 100644
--- a/util/iova-tree.c
+++ b/util/iova-tree.c
@@ -42,12 +42,12 @@ 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 };
 
@@ -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);
-- 
2.27.0

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

[Peter Xu]

On Tue, Oct 12, 2021 at 05:50:01PM +0200, 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>

-- 
Peter Xu

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

[Philippe Mathieu-Daudé]

On 10/12/21 17:50, 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>
> ---
>  include/qemu/iova-tree.h |  8 ++++----
>  hw/i386/intel_iommu.c    |  2 +-
>  util/iova-tree.c         | 10 +++++-----
>  3 files changed, 10 insertions(+), 10 deletions(-)

> -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 };

You missed this one ^

With it declared const:
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

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

[Eugenio Perez Martin]

On Wed, Oct 13, 2021 at 12:21 AM Philippe Mathieu-Daudé
<philmd@redhat.com> wrote:
>
> On 10/12/21 17:50, 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>
> > ---
> >  include/qemu/iova-tree.h |  8 ++++----
> >  hw/i386/intel_iommu.c    |  2 +-
> >  util/iova-tree.c         | 10 +++++-----
> >  3 files changed, 10 insertions(+), 10 deletions(-)
>
> > -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 };
>
> You missed this one ^
>
> With it declared const:
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>

Right! Sending v2.

Thanks!