Merge pull request google#60 from gendx/fix-dynamic-deferred-call

Import bugfix from tock/tock#1636 as a patch.

patches/tock/04-fix-dynamic-deferred-call.patch

@@ -0,0 +1,46 @@
+diff --git a/kernel/src/common/dynamic_deferred_call.rs b/kernel/src/common/dynamic_deferred_call.rs
+index 53f5143d..ca349972 100644
+--- a/kernel/src/common/dynamic_deferred_call.rs
++++ b/kernel/src/common/dynamic_deferred_call.rs
+@@ -226,23 +226,25 @@ impl DynamicDeferredCall {
+     /// `call_global_instance_while`.
+     pub(self) fn call_while<F: Fn() -> bool>(&self, f: F) {
+         if self.call_pending.get() {
+-            // Reset call_pending here, as it may be set again in the deferred calls
+-            self.call_pending.set(false);
++            for (i, client_state) in self.client_states.iter().enumerate() {
++                if !f() {
++                    break;
++                }
++                if client_state.scheduled.get() {
++                    client_state.client.map(|client| {
++                        client_state.scheduled.set(false);
++                        client.call(DeferredCallHandle(i));
++                    });
++                }
++            }
+
+-            self.client_states
+-                .iter()
+-                .enumerate()
+-                .filter(|(_i, client_state)| client_state.scheduled.get())
+-                .filter_map(|(i, client_state)| {
+-                    client_state
+-                        .client
+-                        .map(|c| (i, &client_state.scheduled, *c))
+-                })
+-                .take_while(|_| f())
+-                .for_each(|(i, call_reqd, client)| {
+-                    call_reqd.set(false);
+-                    client.call(DeferredCallHandle(i));
+-                });
++            // Recompute call_pending here, as some deferred calls may have been skipped due to the
++            // `f` predicate becoming false.
++            self.call_pending.set(
++                self.client_states
++                    .iter()
++                    .any(|client_state| client_state.scheduled.get()),
++            );
+         }
+     }
+ }