Safely handle attempts to borrow from closed Ractors

gc.c

@@ -3764,7 +3764,7 @@ mark_received_received_obj_tbl(rb_objspace_t *objspace)
 }
 
 static void
-removed_received_obj_list(rb_objspace_t *objspace, uintptr_t borrowing_id)
+remove_received_obj_list(rb_objspace_t *objspace, uintptr_t borrowing_id)
 {
     rb_native_mutex_lock(&objspace->received_obj_tbl_lock);
     st_data_t data;
@@ -3899,7 +3899,9 @@ borrowing_exit(VALUE args)
 
     if (!!finished_target) {
 	rb_borrowing_sync_lock(finished_target);
-	removed_received_obj_list(finished_target->local_objspace, finished_borrowing_id);
+	if (LIKELY(!finished_target->borrowing_sync.borrowing_closed)) {
+	    remove_received_obj_list(finished_target->local_objspace, finished_borrowing_id);
+	}
 	rb_borrowing_sync_unlock(finished_target);
 	borrowing_count_decrement(finished_target);
 #if VM_CHECK_MODE > 0
@@ -3927,7 +3929,7 @@ run_redirected_func(VALUE args)
 }
 
 VALUE
-rb_run_with_redirected_allocation(rb_ractor_t *target_ractor, VALUE (*func)(VALUE), VALUE func_args)
+rb_attempt_run_with_redirected_allocation(rb_ractor_t *target_ractor, VALUE (*func)(VALUE), VALUE func_args, bool *borrowing_success)
 {
     struct borrowing_data_args borrowing_data = {
 	.borrower = GET_RACTOR(),
@@ -3939,7 +3941,28 @@ rb_run_with_redirected_allocation(rb_ractor_t *target_ractor, VALUE (*func)(VALU
     };
     VALUE bd_args = (VALUE)&borrowing_data;
     borrowing_enter(bd_args);
-    return rb_ensure(run_redirected_func, bd_args, borrowing_exit, bd_args);
+    if (UNLIKELY(target_ractor && target_ractor->borrowing_sync.borrowing_closed)) {
+	if (borrowing_success) *borrowing_success = false;
+	borrowing_exit(bd_args);
+	return Qfalse;
+    }
+    else {
+	if (borrowing_success) *borrowing_success = true;
+	return rb_ensure(run_redirected_func, bd_args, borrowing_exit, bd_args);
+    }
+}
+
+VALUE
+rb_run_with_redirected_allocation(rb_ractor_t *target_ractor, VALUE (*func)(VALUE), VALUE func_args)
+{
+    bool success;
+    VALUE ret = rb_attempt_run_with_redirected_allocation(target_ractor, func, func_args, &success);
+    if (LIKELY(success)) {
+	return ret;
+    }
+    else {
+	rb_bug("Failed to borrow from Ractor #%d", target_ractor->pub.id);
+    }
 }
 
 bool

ractor.c

@@ -1103,7 +1103,7 @@ ractor_send(rb_execution_context_t *ec, rb_ractor_t *r, VALUE obj, VALUE move)
 	.success = false,
     };
 
-    VALUE ret = rb_run_with_redirected_allocation(r, ractor_send_given_redirected_allocation, (VALUE)&args);
+    VALUE ret = rb_attempt_run_with_redirected_allocation(r, ractor_send_given_redirected_allocation, (VALUE)&args, NULL);
     if (!args.success) {
         rb_raise(rb_eRactorClosedError, "The incoming-port is already closed");
     }
@@ -2374,6 +2374,7 @@ rb_ractor_teardown(rb_execution_context_t *ec)
     rb_ractor_t *cr = rb_ec_ractor_ptr(ec);
     rb_borrowing_sync_lock(cr);
     rb_ractor_wait_for_no_borrowers(cr);
+    cr->borrowing_sync.borrowing_closed = true;
     ractor_close_incoming(ec, cr);
     ractor_close_outgoing(ec, cr);
     rb_borrowing_sync_unlock(cr);

ractor_core.h

@@ -224,6 +224,7 @@ struct rb_ractor_struct {
 	rb_atomic_t borrower_count;
 	rb_nativethread_cond_t no_borrowers;
 
+	bool borrowing_closed;
 	bool borrowing_allowed;
 	rb_nativethread_cond_t borrowing_allowed_cond;
 	rb_nativethread_lock_t borrowing_allowed_lock;

vm_core.h

@@ -1818,6 +1818,7 @@ VALUE rb_binding_alloc(VALUE klass);
 VALUE rb_proc_alloc(VALUE klass);
 VALUE rb_proc_dup(VALUE self);
 
+VALUE rb_attempt_run_with_redirected_allocation(rb_ractor_t *target_ractor, VALUE (*func)(VALUE), VALUE func_args, bool *borrowing_success);
 VALUE rb_run_with_redirected_allocation(rb_ractor_t *target_ractor, VALUE (*func)(VALUE), VALUE args);
 bool rb_redirecting_allocation(void);
 rb_ractor_t *rb_current_allocating_ractor(void);