fix tombstones

Author: maurycy

Lib/test/test_external_inspection.py

@@ -1471,6 +1471,60 @@ def matches_awaited_by_pattern(task):
             finally:
                 _cleanup_sockets(client_socket, server_socket)
 
+    @skip_if_not_supported
+    @unittest.skipIf(
+        sys.platform == "linux" and not PROCESS_VM_READV_SUPPORTED,
+        "Test only runs on Linux with process_vm_readv support",
+    )
+    def test_async_global_awaited_by_skips_set_tombstones(self):
+        script_body = """\
+            import asyncio
+
+            class RemovedTask(asyncio.Task):
+                def __hash__(self):
+                    return 0
+
+            class RemainingTask(asyncio.Task):
+                def __hash__(self):
+                    return 1
+
+            async def wait_forever():
+                await asyncio.Event().wait()
+
+            async def main():
+                victim = asyncio.create_task(wait_forever(), name="victim")
+                removed = RemovedTask(wait_forever(), name="removed")
+                remaining = RemainingTask(wait_forever(), name="remaining")
+
+                asyncio.future_add_to_awaited_by(victim, removed)
+                asyncio.future_add_to_awaited_by(victim, remaining)
+
+                # Put a dummy in slot 0 before the only active entry in
+                # slot 1. It must not count toward the set's used entries.
+                asyncio.future_discard_from_awaited_by(victim, removed)
+
+                sock.sendall(b"ready")
+                sock.recv(16)
+
+            asyncio.run(main())
+            """
+
+        with self._target_process(script_body) as (p, client_socket, _):
+            _wait_for_signal(client_socket, b"ready")
+
+            all_awaited_by = get_all_awaited_by(p.pid)
+            tasks_by_name = {
+                task.task_name: task
+                for task in self._get_task_id_map(all_awaited_by).values()
+            }
+            victim = tasks_by_name["victim"]
+            remaining = tasks_by_name["remaining"]
+            self.assertEqual(
+                [waiter.task_name for waiter in victim.awaited_by],
+                [remaining.task_id],
+            )
+            client_socket.sendall(b"done")
+
     @skip_if_not_supported
     @unittest.skipIf(
         sys.platform == "linux" and not PROCESS_VM_READV_SUPPORTED,

Modules/_remote_debugging/asyncio.c

@@ -145,19 +145,22 @@ iterate_set_entries(
     Py_ssize_t i = 0;
     Py_ssize_t els = 0;
     while (i < set_len && els < num_els) {
-        uintptr_t key_addr;
-        if (read_py_ptr(unwinder, table_ptr, &key_addr) < 0) {
+        setentry entry;
+        if (_Py_RemoteDebug_PagedReadRemoteMemory(
+                &unwinder->handle, table_ptr, sizeof(entry), &entry) < 0)
+        {
             set_exception_cause(unwinder, PyExc_RuntimeError, "Failed to read set entry key");
             return -1;
         }
 
-        if ((void*)key_addr != NULL) {
+        uintptr_t key_addr = (uintptr_t)entry.key;
+        if (key_addr != 0 && entry.hash != -1) {
             if (parse_task(unwinder, key_addr, awaited_by) < 0) {
                 return -1;
             }
             els++;
         }
-        table_ptr += sizeof(void*) * 2;
+        table_ptr += sizeof(entry);
         i++;
     }