Use more wait_events

kernel/src/device/pty/pty.rs

@@ -89,6 +89,19 @@ impl PtyMaster {
         self.output.buffer_len()
     }
 
+    fn try_read(&self, writer: &mut VmWriter) -> Result<usize> {
+        let mut input = self.input.disable_irq().lock();
+
+        if input.is_empty() {
+            return_errno_with_message!(Errno::EAGAIN, "the buffer is empty");
+        }
+
+        let read_len = input.read_fallible(writer)?;
+        self.update_state(&input);
+
+        Ok(read_len)
+    }
+
     fn update_state(&self, buf: &RingBuffer<u8>) {
         if buf.is_empty() {
             self.pollee.del_events(IoEvents::IN)
@@ -120,35 +133,12 @@ impl Pollable for PtyMaster {
 
 impl FileIo for PtyMaster {
     fn read(&self, writer: &mut VmWriter) -> Result<usize> {
-        let read_len = writer.avail();
+        if !writer.has_avail() {
-        // TODO: deal with nonblocking read
-        if read_len == 0 {
             return Ok(0);
         }
 
-        let mut poller = Poller::new();
+        // TODO: deal with nonblocking and timeout
-        loop {
+        self.wait_events(IoEvents::IN, || self.try_read(writer))
-            let mut input = self.input.disable_irq().lock();
-
-            if input.is_empty() {
-                let events = self.pollee.poll(IoEvents::IN, Some(&mut poller));
-
-                if events.contains(IoEvents::ERR) {
-                    return_errno_with_message!(Errno::EACCES, "unexpected err");
-                }
-
-                if events.is_empty() {
-                    drop(input);
-                    // FIXME: deal with pty read timeout
-                    poller.wait()?;
-                }
-                continue;
-            }
-
-            let read_len = input.read_fallible(writer)?;
-            self.update_state(&input);
-            return Ok(read_len);
-        }
     }
 
     fn write(&self, reader: &mut VmReader) -> Result<usize> {

kernel/src/device/tty/line_discipline.rs

@@ -16,7 +16,7 @@ use crate::{
     process::signal::{
         constants::{SIGINT, SIGQUIT},
         signals::kernel::KernelSignal,
-        Pollee, Poller,
+        Pollable, Pollee, Poller,
     },
     thread::work_queue::{submit_work_item, work_item::WorkItem, WorkPriority},
     util::ring_buffer::RingBuffer,
@@ -87,6 +87,12 @@ impl CurrentLine {
     }
 }
 
+impl Pollable for LineDiscipline {
+    fn poll(&self, mask: IoEvents, poller: Option<&mut Poller>) -> IoEvents {
+        self.pollee.poll(mask, poller)
+    }
+}
+
 impl LineDiscipline {
     /// Creates a new line discipline
     pub fn new(send_signal: LdiscSignalSender) -> Arc<Self> {
@@ -229,19 +235,7 @@ impl LineDiscipline {
     }
 
     pub fn read(&self, buf: &mut [u8]) -> Result<usize> {
-        loop {
+        self.wait_events(IoEvents::IN, || self.try_read(buf))
-            let res = self.try_read(buf);
-            match res {
-                Ok(len) => return Ok(len),
-                Err(e) if e.error() != Errno::EAGAIN => return Err(e),
-                Err(_) => {
-                    let mut poller = Poller::new();
-                    if self.poll(IoEvents::IN, Some(&mut poller)).is_empty() {
-                        poller.wait()?
-                    }
-                }
-            }
-        }
     }
 
     /// Reads all bytes buffered to `dst`.
@@ -275,10 +269,6 @@ impl LineDiscipline {
         Ok(read_len)
     }
 
-    pub fn poll(&self, mask: IoEvents, poller: Option<&mut Poller>) -> IoEvents {
-        self.pollee.poll(mask, poller)
-    }
-
     /// Reads bytes from `self` to `dst`, returning the actual bytes read.
     ///
     /// If no bytes are available, this method returns 0 immediately.

kernel/src/syscall/eventfd.rs

@@ -130,6 +130,28 @@ impl EventFile {
         // TODO: deal with overflow logic
     }
 
+    fn try_read(&self, writer: &mut VmWriter) -> Result<()> {
+        let mut counter = self.counter.lock();
+
+        // Wait until the counter becomes non-zero
+        if *counter == 0 {
+            return_errno_with_message!(Errno::EAGAIN, "the counter is zero");
+        }
+
+        // Copy value from counter, and set the new counter value
+        if self.flags.lock().contains(Flags::EFD_SEMAPHORE) {
+            writer.write_fallible(&mut 1u64.as_bytes().into())?;
+            *counter -= 1;
+        } else {
+            writer.write_fallible(&mut (*counter).as_bytes().into())?;
+            *counter = 0;
+        }
+
+        self.update_io_state(&counter);
+
+        Ok(())
+    }
+
     /// Adds val to the counter.
     ///
     /// If the new_value is overflowed or exceeds MAX_COUNTER_VALUE, the counter value
@@ -160,40 +182,15 @@ impl Pollable for EventFile {
 impl FileLike for EventFile {
     fn read(&self, writer: &mut VmWriter) -> Result<usize> {
         let read_len = core::mem::size_of::<u64>();
+
         if writer.avail() < read_len {
             return_errno_with_message!(Errno::EINVAL, "buf len is less len u64 size");
         }
 
-        loop {
+        if self.is_nonblocking() {
-            let mut counter = self.counter.lock();
+            self.try_read(writer)?;
-
+        } else {
-            // Wait until the counter becomes non-zero
+            self.wait_events(IoEvents::IN, || self.try_read(writer))?;
-            if *counter == 0 {
-                if self.is_nonblocking() {
-                    return_errno_with_message!(Errno::EAGAIN, "try reading event file again");
-                }
-
-                self.update_io_state(&counter);
-                drop(counter);
-
-                let mut poller = Poller::new();
-                if self.pollee.poll(IoEvents::IN, Some(&mut poller)).is_empty() {
-                    poller.wait()?;
-                }
-                continue;
-            }
-
-            // Copy value from counter, and set the new counter value
-            if self.flags.lock().contains(Flags::EFD_SEMAPHORE) {
-                writer.write_fallible(&mut 1u64.as_bytes().into())?;
-                *counter -= 1;
-            } else {
-                writer.write_fallible(&mut (*counter).as_bytes().into())?;
-                *counter = 0;
-            }
-
-            self.update_io_state(&counter);
-            break;
         }
 
         Ok(read_len)