sched: migrate timers

When we migrate a thread, remove its timers from the cpu-local timer list,
and move them back when we complete migration.

core/sched.cc

@@ -59,6 +59,9 @@ void cpu::handle_incoming_wakeups()
             q.pop_front_nonatomic();
             t._on_runqueue = true;
             runqueue.push_back(t);
+            with_lock(irq_lock, [&] {
+                t.resume_timers();
+            });
         }
     }
 }
@@ -95,6 +98,7 @@ void cpu::load_balance()
             auto& mig = runqueue.back();
             runqueue.pop_back();
             // we won't race with wake(), since we're not _waiting
+            mig.suspend_timers();
             mig._cpu = min;
             min->incoming_wakeups[id].push_front(mig);
             // FIXME: IPI
@@ -148,6 +152,7 @@ thread::thread(std::function<void ()> func, attr attr, bool main)
     , _waiting(false)
     , _attr(attr)
     , _terminated(false)
+    , _timers_need_reload()
     , _joiner()
 {
     with_lock(thread_list_mutex, [this] {
@@ -233,6 +238,28 @@ void thread::complete()
     }
 }
 
+void thread::suspend_timers()
+{
+    if (_timers_need_reload) {
+        return;
+    }
+    _timers_need_reload = true;
+    for (auto& t : _active_timers) {
+        _cpu->timers.suspend(t);
+    }
+}
+
+void thread::resume_timers()
+{
+    if (!_timers_need_reload) {
+        return;
+    }
+    _timers_need_reload = false;
+    for (auto& t : _active_timers) {
+        _cpu->timers.resume(t);
+    }
+}
+
 void thread::join()
 {
     _joiner = current();
@@ -263,6 +290,29 @@ void timer_list::fired()
     }
 }
 
+// call with irq disabled
+void timer_list::suspend(bi::list<timer>& timers)
+{
+    for (auto& t : timers) {
+        assert(!t._expired);
+        _list.erase(_list.iterator_to(t));
+    }
+}
+
+// call with irq disabled
+void timer_list::resume(bi::list<timer>& timers)
+{
+    bool rearm = false;
+    for (auto& t : timers) {
+        assert(!t._expired);
+        auto i = _list.insert(t).first;
+        rearm |= i == _list.begin();
+    }
+    if (rearm) {
+        clock_event->set(_list.begin()->_time);
+    }
+}
+
 void timer_list::callback_dispatch::fired()
 {
     cpu::current()->timers.fired();
@@ -309,7 +359,7 @@ void timer::cancel()
             return;
         }
         _t._active_timers.erase(_t._active_timers.iterator_to(*this));
-        _t._cpu->timers._list.erase(*this);
+        _t._cpu->timers._list.erase(_t._cpu->timers._list.iterator_to(*this));
         _expired = false;
     });
     // even if we remove the first timer, allow it to expire rather than

include/sched.hh

@@ -87,6 +87,8 @@ private:
     void init_stack();
     void setup_tcb();
     void complete();
+    void suspend_timers();
+    void resume_timers();
     static void on_thread_stack(thread* t);
 private:
     std::function<void ()> _func;
@@ -97,6 +99,7 @@ private:
     attr _attr;
     cpu* _cpu;
     bool _terminated;
+    bool _timers_need_reload;
     bi::list<timer> _active_timers;
     friend void thread_main_c(thread* t);
     friend class wait_guard;
@@ -117,6 +120,8 @@ public:
 class timer_list {
 public:
     void fired();
+    void suspend(bi::list<timer>& t);
+    void resume(bi::list<timer>& t);
 private:
     friend class timer;
     bi::set<timer, bi::base_hook<bi::set_base_hook<>>> _list;