增加epoll机制 (#455)

* ## 增加epoll机制
- 增加epoll机制
- 添加事件等待队列，提升socket性能
- 优化poll，删除不能poll的文件系统中的poll方法

* 添加细节注释

* 修复文件关闭后epoll还持有对应描述符的文件弱引用的bug

* 将EPollEvent设计为POSIX标准

* 修改s到us转换的计算错误

kernel/src/driver/disk/ahci/ahci_inode.rs

@@ -4,7 +4,7 @@ use crate::filesystem::vfs::file::FileMode;
 use crate::filesystem::vfs::syscall::ModeType;
 use crate::filesystem::vfs::{
     core::generate_inode_id, make_rawdev, FilePrivateData, FileSystem, FileType, IndexNode,
-    Metadata, PollStatus,
+    Metadata,
 };
 use crate::syscall::SystemError;
 use crate::{libs::spinlock::SpinLock, time::TimeSpec};
@@ -108,10 +108,6 @@ impl IndexNode for LockedAhciInode {
         return Ok(());
     }
 
-    fn poll(&self) -> Result<PollStatus, SystemError> {
-        return Ok(PollStatus::READ | PollStatus::WRITE);
-    }
-
     /// 读设备 - 应该调用设备的函数读写，而不是通过文件系统读写
     fn read_at(
         &self,

kernel/src/driver/keyboard/ps2_keyboard.rs

@@ -8,7 +8,7 @@ use crate::{
         devfs::{devfs_register, DevFS, DeviceINode},
         vfs::{
             core::generate_inode_id, file::FileMode, syscall::ModeType, FileType, IndexNode,
-            Metadata, PollStatus,
+            Metadata,
         },
     },
     include::bindings::bindings::vfs_file_operations_t,
@@ -152,10 +152,6 @@ impl IndexNode for LockedPS2KeyBoardInode {
         return Ok(());
     }
 
-    fn poll(&self) -> Result<PollStatus, SystemError> {
-        return Ok(PollStatus::READ);
-    }
-
     fn metadata(&self) -> Result<Metadata, SystemError> {
         return Ok(self.0.read().metadata.clone());
     }

kernel/src/driver/net/virtio_net.rs

@@ -165,7 +165,7 @@ impl<T: Transport> phy::Device for VirtioNICDriver<T> {
 
     fn transmit(&mut self, _timestamp: smoltcp::time::Instant) -> Option<Self::TxToken<'_>> {
         // kdebug!("VirtioNet: transmit");
-        if self.inner.lock().can_send() {
+        if self.inner.lock_irqsave().can_send() {
             // kdebug!("VirtioNet: can send");
             return Some(VirtioNetToken::new(self.clone(), None));
         } else {

kernel/src/driver/tty/tty_device.rs

@@ -214,10 +214,6 @@ impl IndexNode for TtyDevice {
         return Err(SystemError::EIO);
     }
 
-    fn poll(&self) -> Result<crate::filesystem::vfs::PollStatus, SystemError> {
-        return Err(SystemError::EOPNOTSUPP_OR_ENOTSUP);
-    }
-
     fn fs(&self) -> Arc<dyn crate::filesystem::vfs::FileSystem> {
         return self.fs.read().upgrade().unwrap();
     }