commit c65a406abd9d846dfffa9969be6af4e4de97b213
author Chuanxiao Dong <chuanxiao.dong@intel.corp-partner.google.com> Mon Jan 13 10:36:59 2020 +0800
committer Commit Bot <commit-bot@chromium.org> Thu Feb 06 14:34:57 2020 +0000
tree 193d723a9842d480dc0761f702fc72f2e37fe43e
parent fab42c86ed2aa0ead9c66efdea7adf51975258fb

vhost-net: implement the reset method

Vhost-net reset method can stop the activate thread and let it to
return the ownership of eventfds and tap back to the device, so that
it is possible to be activated again.

BUG=None
TEST=launch Crosvm guest with vhost-net. It works fine with iperf test.
TEST=cargo test -p devices

Change-Id: I8f3cb6939595b4dffa0e95bcffbf9fcc8fcf71ba
Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.corp-partner.google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2009665
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>

devices/src/virtio/vhost/net.rs

diff --git a/devices/src/virtio/vhost/net.rs b/devices/src/virtio/vhost/net.rs
index e9dcf14..ff72970 100644
--- a/devices/src/virtio/vhost/net.rs
+++ b/devices/src/virtio/vhost/net.rs
@@ -25,7 +25,7 @@
 pub struct Net<T: TapT, U: VhostNetT<T>> {
     workers_kill_evt: Option<EventFd>,
     kill_evt: EventFd,
-    worker_thread: Option<thread::JoinHandle<()>>,
+    worker_thread: Option<thread::JoinHandle<(Worker<U>, T)>>,
     tap: Option<T>,
     vhost_net_handle: Option<U>,
     vhost_interrupt: Option<Vec<EventFd>>,
@@ -141,6 +141,7 @@
         if let Some(workers_kill_evt) = &self.workers_kill_evt {
             keep_fds.push(workers_kill_evt.as_raw_fd());
         }
+        keep_fds.push(self.kill_evt.as_raw_fd());
 
         keep_fds
     }
@@ -220,6 +221,7 @@
                                 if let Err(e) = result {
                                     error!("net worker thread exited with error: {}", e);
                                 }
+                                (worker, tap)
                             });
 
                         match worker_result {
@@ -248,6 +250,31 @@
             }
         }
     }
+
+    fn reset(&mut self) -> bool {
+        // Only kill the child if it claimed its eventfd.
+        if self.workers_kill_evt.is_none() && self.kill_evt.write(1).is_err() {
+            error!("{}: failed to notify the kill event", self.debug_label());
+            return false;
+        }
+
+        if let Some(worker_thread) = self.worker_thread.take() {
+            match worker_thread.join() {
+                Err(_) => {
+                    error!("{}: failed to get back resources", self.debug_label());
+                    return false;
+                }
+                Ok((worker, tap)) => {
+                    self.vhost_net_handle = Some(worker.vhost_handle);
+                    self.tap = Some(tap);
+                    self.vhost_interrupt = Some(worker.vhost_interrupt);
+                    self.workers_kill_evt = Some(worker.kill_evt);
+                    return true;
+                }
+            }
+        }
+        false
+    }
 }
 
 #[cfg(test)]

devices/src/virtio/vhost/worker.rs

diff --git a/devices/src/virtio/vhost/worker.rs b/devices/src/virtio/vhost/worker.rs
index 630edaa..1eff01f 100644
--- a/devices/src/virtio/vhost/worker.rs
+++ b/devices/src/virtio/vhost/worker.rs
@@ -17,10 +17,10 @@
 pub struct Worker<T: Vhost> {
     interrupt: Interrupt,
     queues: Vec<Queue>,
-    vhost_handle: T,
-    vhost_interrupt: Vec<EventFd>,
+    pub vhost_handle: T,
+    pub vhost_interrupt: Vec<EventFd>,
     acked_features: u64,
-    kill_evt: EventFd,
+    pub kill_evt: EventFd,
 }
 
 impl<T: Vhost> Worker<T> {
@@ -130,7 +130,10 @@
                     Token::InterruptResample => {
                         self.interrupt.interrupt_resample();
                     }
-                    Token::Kill => break 'poll,
+                    Token::Kill => {
+                        let _ = self.kill_evt.read();
+                        break 'poll;
+                    }
                 }
             }
         }