rusticl/mesa: add thread-safe wrapper for pipe_image_views

In theory a pipe_image_view can outlive the pipe_resource it's referring
to, so we have to make sure that doesn't happen.

Signed-off-by: Karol Herbst <kherbst@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26040>

src/gallium/frontends/rusticl/mesa/pipe/context.rs

@@ -520,7 +520,8 @@ impl PipeContext {
         unsafe { self.pipe.as_ref().sampler_view_destroy.unwrap()(self.pipe.as_ptr(), view) }
     }
 
-    pub fn set_shader_images(&self, images: &[pipe_image_view]) {
+    pub fn set_shader_images(&self, images: &[PipeImageView]) {
+        let images = PipeImageView::slice_to_pipe(images);
         unsafe {
             self.pipe.as_ref().set_shader_images.unwrap()(
                 self.pipe.as_ptr(),

src/gallium/frontends/rusticl/mesa/pipe/resource.rs

@@ -1,6 +1,6 @@
 use mesa_rust_gen::*;
 
-use std::ptr;
+use std::{mem, ptr};
 
 #[derive(PartialEq, Eq, Hash)]
 pub struct PipeResource {
@@ -12,6 +12,37 @@ pub struct PipeResource {
 unsafe impl Send for PipeResource {}
 unsafe impl Sync for PipeResource {}
 
+/// A thread safe wrapper around [pipe_image_view]. It's purpose is to increase the reference count
+/// on the [pipe_resource] this view belongs to.
+#[repr(transparent)]
+pub struct PipeImageView {
+    pub(super) pipe: pipe_image_view,
+}
+
+impl PipeImageView {
+    fn new(pipe: pipe_image_view) -> Self {
+        unsafe { pipe_resource_reference(&mut ptr::null_mut(), pipe.resource) }
+        Self { pipe: pipe }
+    }
+
+    pub fn slice_to_pipe(slice: &[PipeImageView]) -> &[pipe_image_view] {
+        // SAFETY: `PipeImageView` is a transparent wrapper around `pipe_image_view`, so transmute
+        //         on the slice is safe.
+        unsafe { mem::transmute(slice) }
+    }
+}
+
+impl Drop for PipeImageView {
+    fn drop(&mut self) {
+        unsafe { pipe_resource_reference(&mut self.pipe.resource, ptr::null_mut()) }
+    }
+}
+
+// SAFETY: pipe_image_view is just static data around a pipe_resource, which itself is a thread-safe
+//         type.
+unsafe impl Send for PipeImageView {}
+unsafe impl Sync for PipeImageView {}
+
 // Image dimensions provide by application to be used in both
 // image and sampler views when image is created from buffer
 #[derive(PartialEq, Eq)]
@@ -85,7 +116,8 @@ impl PipeResource {
         read_write: bool,
         host_access: u16,
         app_img_info: Option<&AppImgInfo>,
-    ) -> pipe_image_view {
+    ) -> PipeImageView {
+        let pipe = PipeResource::as_ref(self);
         let u = if let Some(app_img_info) = app_img_info {
             pipe_image_view__bindgen_ty_1 {
                 tex2d_from_buf: pipe_image_view__bindgen_ty_1__bindgen_ty_3 {
@@ -99,17 +131,17 @@ impl PipeResource {
             pipe_image_view__bindgen_ty_1 {
                 buf: pipe_image_view__bindgen_ty_1__bindgen_ty_2 {
                     offset: 0,
-                    size: self.as_ref().width0,
+                    size: pipe.width0,
                 },
             }
         } else {
             let mut tex = pipe_image_view__bindgen_ty_1__bindgen_ty_1::default();
             tex.set_level(0);
             tex.set_first_layer(0);
-            if self.as_ref().target() == pipe_texture_target::PIPE_TEXTURE_3D {
-                tex.set_last_layer((self.as_ref().depth0 - 1).into());
-            } else if self.as_ref().array_size > 0 {
-                tex.set_last_layer((self.as_ref().array_size - 1).into());
+            if pipe.target() == pipe_texture_target::PIPE_TEXTURE_3D {
+                tex.set_last_layer((pipe.depth0 - 1).into());
+            } else if pipe.array_size > 0 {
+                tex.set_last_layer((pipe.array_size - 1).into());
             } else {
                 tex.set_last_layer(0);
             }
@@ -129,13 +161,13 @@ impl PipeResource {
             0
         } as u16;
 
-        pipe_image_view {
+        PipeImageView::new(pipe_image_view {
             resource: self.pipe(),
             format: format,
             access: access | host_access,
             shader_access: shader_access,
             u: u,
-        }
+        })
     }
 
     pub fn pipe_sampler_view_template(