xwayland: use io_uring to prevent lockups

See https://gitlab.freedesktop.org/wayland/wayland/-/issues/296

src/io_uring/ops/async_cancel.rs

@@ -0,0 +1,52 @@
+use {
+    crate::{
+        io_uring::{
+            sys::{io_uring_sqe, IORING_OP_ASYNC_CANCEL},
+            IoUringData, Task,
+        },
+        utils::errorfmt::ErrorFmt,
+    },
+    std::cell::Cell,
+};
+
+pub struct AsyncCancelTask {
+    id: Cell<u64>,
+    target: Cell<u64>,
+}
+
+impl IoUringData {
+    pub fn cancel_task_in_kernel(&self, target: u64) {
+        let task = self.cached_cancels.pop().unwrap_or_else(|| {
+            Box::new(AsyncCancelTask {
+                id: Cell::new(0),
+                target: Cell::new(0),
+            })
+        });
+        let id = self.id_raw();
+        task.id.set(id);
+        task.target.set(target);
+        self.schedule(task);
+    }
+}
+
+unsafe impl Task for AsyncCancelTask {
+    fn id(&self) -> u64 {
+        self.id.get()
+    }
+
+    fn complete(self: Box<Self>, ring: &IoUringData, res: i32) {
+        if let Err(e) = map_err!(res) {
+            log::debug!("Could not cancel task: {}", ErrorFmt(e));
+        }
+        ring.cached_cancels.push(self);
+    }
+
+    fn encode(&self, sqe: &mut io_uring_sqe) {
+        sqe.opcode = IORING_OP_ASYNC_CANCEL;
+        sqe.u2.addr = self.target.get();
+    }
+
+    fn is_cancel(&self) -> bool {
+        true
+    }
+}