Fix a potential racing in park() and unpark(), fix sys_poll for a running telnet

crate/thread/src/thread_pool.rs

@@ -131,24 +131,25 @@ impl ThreadPool {
     /// Insert/Remove it to/from scheduler if necessary.
     fn set_status(&self, tid: Tid, status: Status) {
         let mut proc_lock = self.threads[tid].lock();
-        let mut proc = proc_lock.as_mut().expect("process not exist");
-        trace!("process {} {:?} -> {:?}", tid, proc.status, status);
-        match (&proc.status, &status) {
-            (Status::Ready, Status::Ready) => return,
-            (Status::Ready, _) => panic!("can not remove a process from ready queue"),
-            (Status::Exited(_), _) => panic!("can not set status for a exited process"),
-            (Status::Sleeping, Status::Exited(_)) => self.timer.lock().stop(Event::Wakeup(tid)),
-            (Status::Running(_), Status::Ready) => {} // to stop a thread, use stop() intead
-            (_, Status::Ready) => self.scheduler.push(tid),
-            _ => {}
-        }
-        match proc.status {
-            Status::Running(_) => proc.status_after_stop = status,
-            _ => proc.status = status,
-        }
-        match proc.status {
-            Status::Exited(_) => self.exit_handler(tid, proc),
-            _ => {}
+        if let Some(mut proc) = proc_lock.as_mut() {
+            trace!("process {} {:?} -> {:?}", tid, proc.status, status);
+            match (&proc.status, &status) {
+                (Status::Ready, Status::Ready) => return,
+                (Status::Ready, _) => panic!("can not remove a process from ready queue"),
+                (Status::Exited(_), _) => panic!("can not set status for a exited process"),
+                (Status::Sleeping, Status::Exited(_)) => self.timer.lock().stop(Event::Wakeup(tid)),
+                (Status::Running(_), Status::Ready) => {} // process will be added to scheduler in stop() 
+                (_, Status::Ready) => self.scheduler.push(tid),
+                _ => {}
+            }
+            match proc.status {
+                Status::Running(_) => proc.status_after_stop = status,
+                _ => proc.status = status,
+            }
+            match proc.status {
+                Status::Exited(_) => self.exit_handler(tid, proc),
+                _ => {}
+            }
         }
     }
 

kernel/src/backtrace.rs

@@ -72,7 +72,8 @@ pub fn backtrace() {
                 // Kernel stack at 0x0000_57ac_0000_0000 (defined in bootloader crate)
                 // size = 512 pages
                 current_fp = *(current_fp as *const usize).offset(0);
-                if current_fp >= 0x0000_57ac_0000_0000 + 512 * PAGE_SIZE - size_of::<usize>() {
+                if current_fp >= 0x0000_57ac_0000_0000 + 512 * PAGE_SIZE - size_of::<usize>() &&
+                    current_fp <= 0xffff_ff00_0000_0000 {
                     break;
                 }
                 current_pc = *(current_fp as *const usize).offset(1);

kernel/src/syscall/fs.rs

@@ -62,13 +62,15 @@ pub fn sys_poll(ufds: *mut PollFd, nfds: usize, timeout_msecs: usize) -> SysResu
     loop {
         use PollEvents as PE;
         let mut proc = process();
+        let mut events = 0;
         for poll in polls.iter_mut() {
+            poll.revents = PE::NONE;
             match proc.files.get(&(poll.fd as usize)) {
                 Some(FileLike::File(_)) => {
                     // FIXME: assume it is stdin for now
                     if poll.events.contains(PE::IN) && STDIN.can_read() {
-                        poll.revents = PE::IN;
-                        return Ok(0);
+                        poll.revents = poll.revents | PE::IN;
+                        events = events + 1;
                     }
                 },
                 Some(FileLike::Socket(wrapper)) => {
@@ -78,29 +80,42 @@ pub fn sys_poll(ufds: *mut PollFd, nfds: usize, timeout_msecs: usize) -> SysResu
                         let mut socket = sockets.get::<TcpSocket>(wrapper.handle);
 
                         if !socket.is_open() {
-                            poll.revents = PE::HUP;
-                            return Ok(0);
-                        } else if socket.can_recv() && poll.events.contains(PE::IN) {
-                            poll.revents = PE::IN;
-                            return Ok(0);
-                        } else if socket.can_send() && poll.events.contains(PE::OUT) {
-                            poll.revents = PE::OUT;
-                            return Ok(0);
+                            poll.revents = poll.revents | PE::HUP;
+                            events = events + 1;
+                        } else {
+                            if socket.can_recv() && poll.events.contains(PE::IN) {
+                                poll.revents = poll.revents | PE::IN;
+                                events = events + 1;
+                            }
+
+                            if socket.can_send() && poll.events.contains(PE::OUT) {
+                                poll.revents = poll.revents | PE::OUT;
+                                events = events + 1;
+                            }
                         }                    
                     } else {
                         unimplemented!()
                     }
                 }
                 None => {
-                    poll.revents = PE::ERR;
-                    return Ok(0);
+                    poll.revents = poll.revents | PE::ERR;
+                    events = events + 1;
                 }
             }
         }
         drop(proc);
+
+        if events > 0 {
+            return Ok(events as isize);
+        }
+
+        let current_time_ms = unsafe {crate::trap::TICK / crate::consts::USEC_PER_TICK / 1000};
+        if timeout_msecs < (1 << 31) && current_time_ms - begin_time_ms > timeout_msecs {
+            return Ok(0);
+        }
+
         Condvar::wait_any(&[&STDIN.pushed, &(*SOCKET_ACTIVITY)]);
     }
-    Ok(nfds as isize)
 }
 
 pub fn sys_readv(fd: usize, iov_ptr: *const IoVec, iov_count: usize) -> SysResult {
@@ -704,6 +719,8 @@ pub struct PollFd {
 
 bitflags! {
     pub struct PollEvents: u16 {
+        /// Nothing Happens
+        const NONE = 0x0000;
         /// There is data to read.
         const IN = 0x0001;
         /// Writing is now possible.

kernel/src/syscall/net.rs

@@ -294,6 +294,7 @@ pub fn sys_read_socket(proc: &mut Process, fd: usize, base: *mut u8, len: usize)
 
             // avoid deadlock
             drop(socket);
+            drop(sockets);
             SOCKET_ACTIVITY._wait()
         }
     } else if let SocketType::Udp = wrapper.socket_type {