fix: revert change_state conditional reorder and sigurg_handler Syscall check, reorder WriteSyscallFacade to match impl_facade!

Agent-Logs-Url: https://github.com/acl-dev/open-coroutine/sessions/6b5b9353-541a-4b6b-9636-2fdee16b53fd

Co-authored-by: loongs-zhang <38336731+loongs-zhang@users.noreply.github.com>

Author: Copilot

core/src/coroutine/state.rs

@@ -18,26 +18,11 @@ where
         new_state: CoroutineState<Yield, Return>,
     ) -> CoroutineState<Yield, Return> {
         let old_state = self.state.replace(new_state);
-        //对→Running的转换：先记录日志再通知MonitorListener。
-        //on_state_changed(Running)会通过MonitorListener设置10ms的NOTIFY_NODE定时器，
-        //如果先通知再记录日志，在QEMU等慢平台上info!()可能耗时>10ms，
-        //导致定时器在日志记录期间过期→SIGURG→抢占活锁。
-        //先记录日志确保NOTIFY_NODE定时器在日志I/O完成后才启动。
-        // For →Running transitions: log BEFORE notifying MonitorListener.
-        // on_state_changed(Running) sets a 10ms NOTIFY_NODE timer via MonitorListener.
-        // If notified first, info!() can take >10ms on slow platforms (QEMU),
-        // causing the timer to expire during logging → SIGURG → preemption live-lock.
-        // Logging first ensures the NOTIFY_NODE timer starts after slow I/O completes.
-        if matches!(new_state, CoroutineState::Running) {
-            info!("{} {:?}->{:?}", self.name(), old_state, new_state);
-            self.on_state_changed(self, old_state, new_state);
+        self.on_state_changed(self, old_state, new_state);
+        if let CoroutineState::Error(_) = new_state {
+            error!("{} {:?}->{:?}", self.name(), old_state, new_state);
         } else {
-            self.on_state_changed(self, old_state, new_state);
-            if let CoroutineState::Error(_) = new_state {
-                error!("{} {:?}->{:?}", self.name(), old_state, new_state);
-            } else {
-                info!("{} {:?}->{:?}", self.name(), old_state, new_state);
-            }
+            info!("{} {:?}->{:?}", self.name(), old_state, new_state);
         }
         old_state
     }

core/src/monitor.rs

@@ -78,24 +78,6 @@ impl Monitor {
                 set.remove(Signal::SIGURG);
                 set.thread_set_mask()
                     .expect("Failed to remove SIGURG signal mask!");
-                //不抢占处于Syscall状态的协程。
-                //MonitorListener的设计理念是不对Syscall状态的协程发送信号。
-                //但由于NOTIFY_NODE移除和monitor线程遍历之间存在竞态条件，
-                //SIGURG可能在协程刚进入Syscall状态时到达。
-                //如果此时抢占，协程会被放入syscall_map但无人唤醒（因为没有io_uring/epoll注册），
-                //导致死锁。
-                // Skip preemption for coroutines in Syscall state.
-                // MonitorListener's design is to NOT send signals to Syscall-state
-                // coroutines. However, a race between NOTIFY_NODE removal and the
-                // monitor's queue iteration can cause SIGURG to arrive just after
-                // the coroutine entered Syscall state. If preempted here, the
-                // coroutine lands in the syscall map with no io_uring/epoll/timer
-                // registration to wake it, causing a deadlock.
-                if let Some(co) = SchedulableCoroutine::current() {
-                    if matches!(co.state(), CoroutineState::Syscall((), _, _)) {
-                        return;
-                    }
-                }
                 if let Some(suspender) = SchedulableSuspender::current() {
                     suspender.suspend();
                 }

core/src/syscall/unix/write.rs

@@ -42,7 +42,6 @@ impl<I: WriteSyscall> WriteSyscall for WriteSyscallFacade<I> {
             return RawWriteSyscall::default().write(fn_ptr, fd, buf, len);
         }
         let syscall = crate::common::constants::SyscallName::write;
-        crate::info!("enter syscall {}", syscall);
         if let Some(co) = crate::scheduler::SchedulableCoroutine::current() {
             let new_state = crate::common::constants::SyscallState::Executing;
             if co.syscall((), syscall, new_state).is_err() {
@@ -51,6 +50,7 @@ impl<I: WriteSyscall> WriteSyscall for WriteSyscallFacade<I> {
                 );
             }
         }
+        crate::info!("enter syscall {}", syscall);
         let r = self.inner.write(fn_ptr, fd, buf, len);
         if let Some(co) = crate::scheduler::SchedulableCoroutine::current() {
             if co.running().is_err() {