rusticl: add a safe abstraction to execute a MemCB

Reviewed-by: Karol Herbst <kherbst@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25669>

src/gallium/frontends/rusticl/api/types.rs

@@ -2,6 +2,7 @@ use crate::api::icd::CLResult;
 use crate::api::icd::ReferenceCountedAPIPointer;
 use crate::core::context::Context;
 use crate::core::event::Event;
+use crate::core::memory::Mem;
 
 use rusticl_opencl_gen::*;
 
@@ -146,6 +147,15 @@ cl_callback!(
     }
 );
 
+impl MemCB {
+    pub fn call(self, mem: &Mem) {
+        let cl = cl_mem::from_ptr(mem);
+        // SAFETY: `cl` must have pointed to an OpenCL context, which is where we just got it from.
+        // All other requirements are covered by this callback's type invariants.
+        unsafe { (self.func)(cl, self.data) };
+    }
+}
+
 cl_callback!(
     ProgramCB(FuncProgramCB) {
         program: cl_program,

src/gallium/frontends/rusticl/core/memory.rs

@@ -21,6 +21,7 @@ use std::cmp;
 use std::collections::hash_map::Entry;
 use std::collections::HashMap;
 use std::convert::TryInto;
+use std::mem;
 use std::mem::size_of;
 use std::ops::AddAssign;
 use std::os::raw::c_void;
@@ -1234,13 +1235,10 @@ impl Mem {
 
 impl Drop for Mem {
     fn drop(&mut self) {
-        let cl = cl_mem::from_ptr(self);
-        self.cbs
-            .get_mut()
-            .unwrap()
-            .iter()
-            .rev()
-            .for_each(|cb| unsafe { (cb.func)(cl, cb.data) });
+        let cbs = mem::take(self.cbs.get_mut().unwrap());
+        for cb in cbs.into_iter().rev() {
+            cb.call(self);
+        }
 
         for (d, tx) in self.maps.get_mut().unwrap().tx.drain() {
             d.helper_ctx().unmap(tx.tx);