dbs-virtio-devices: Clear resources when removing virtio devices

This PR implements functionaility of clearing resources for virtio-net
and virtio-vsock devices.

For virtio-net devices, the removed resource is its event hanlder.

For virtio-vsock devices, the removed resources are its event handler
and a socket on the host.

Fixes: #273

Signed-off-by: Zizheng Bian <zizheng.bian@linux.alibaba.com>
Signed-off-by: Xuewei Niu <niuxuewei.nxw@antgroup.com>

crates/dbs-virtio-devices/src/net.rs

@@ -22,7 +22,7 @@ use dbs_utils::metric::{IncMetric, SharedIncMetric};
 use dbs_utils::net::{net_gen, MacAddr, Tap, MAC_ADDR_LEN};
 use dbs_utils::rate_limiter::{BucketUpdate, RateLimiter, TokenType};
 use libc;
-use log::{debug, error, info, trace};
+use log::{debug, error, info, trace, warn};
 use serde::Serialize;
 use virtio_bindings::bindings::virtio_net::*;
 use virtio_queue::{QueueOwnedT, QueueSync, QueueT};
@@ -861,6 +861,18 @@ where
     fn as_any_mut(&mut self) -> &mut dyn Any {
         self
     }
+
+    fn remove(&mut self) {
+        let subscriber_id = self.subscriber_id.take();
+        if let Some(subscriber_id) = subscriber_id {
+            match self.device_info.remove_event_handler(subscriber_id) {
+                Ok(_) => debug!("virtio-net: removed subscriber_id {:?}", subscriber_id),
+                Err(err) => warn!("virtio-net: failed to remove event handler: {:?}", err),
+            };
+        } else {
+            self.tap.take();
+        }
+    }
 }
 
 #[cfg(test)]

crates/dbs-virtio-devices/src/vsock/backend/unix_stream.rs

@@ -91,6 +91,12 @@ impl VsockBackend for VsockUnixStreamBackend {
     }
 }
 
+impl Drop for VsockUnixStreamBackend {
+    fn drop(&mut self) {
+        std::fs::remove_file(&self.host_sock_path).ok();
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use std::fs;

crates/dbs-virtio-devices/src/vsock/device.rs

@@ -12,7 +12,9 @@ use std::sync::Arc;
 
 use dbs_device::resources::ResourceConstraint;
 use dbs_utils::epoll_manager::{EpollManager, SubscriberId};
+use log::debug;
 use log::trace;
+use log::warn;
 use virtio_queue::QueueT;
 use vm_memory::GuestAddressSpace;
 use vm_memory::GuestMemoryRegion;
@@ -187,6 +189,18 @@ where
     fn as_any_mut(&mut self) -> &mut dyn Any {
         self
     }
+
+    fn remove(&mut self) {
+        let subscriber_id = self.subscriber_id.take();
+        if let Some(subscriber_id) = subscriber_id {
+            match self.device_info.remove_event_handler(subscriber_id) {
+                Ok(_) => debug!("virtio-vsock: removed subscriber_id {:?}", subscriber_id),
+                Err(err) => warn!("virtio-vsock: failed to remove event handler: {:?}", err),
+            };
+        } else {
+            self.muxer.take();
+        }
+    }
 }
 
 #[cfg(test)]