devices: join worker threads in drop()

Make sure all devices join any threads they spawn before returning from
the drop() handler after signaling the exit event.

BUG=chromium:992494
TEST=crosvm exits without errors

Change-Id: I6bc91c32a08f568b041765044caa9aff6f7cf4a9
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/1802156
Reviewed-by: Stephen Barber <smbarber@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>

1 files changed, 14 insertions, 3 deletions

diff --git a/devices/src/virtio/gpu/mod.rs b/devices/src/virtio/gpu/mod.rs
index 49787fb..48ee6cb 100644
--- a/devices/src/virtio/gpu/mod.rs
+++ b/devices/src/virtio/gpu/mod.rs
@@ -678,6 +678,7 @@ pub struct Gpu {
     gpu_device_socket: Option<VmMemoryControlRequestSocket>,
     resource_bridges: Vec<ResourceResponseSocket>,
     kill_evt: Option<EventFd>,
+    worker_thread: Option<thread::JoinHandle<()>>,
     num_scanouts: NonZeroU8,
     display_backends: Vec<DisplayBackend>,
 }
@@ -696,6 +697,7 @@ impl Gpu {
             gpu_device_socket,
             resource_bridges,
             kill_evt: None,
+            worker_thread: None,
             num_scanouts,
             display_backends,
         }
@@ -721,6 +723,10 @@ impl Drop for Gpu {
             // Ignore the result because there is nothing we can do about it.
             let _ = kill_evt.write(1);
         }
+
+        if let Some(worker_thread) = self.worker_thread.take() {
+            let _ = worker_thread.join();
+        }
     }
 }
 
@@ -837,9 +843,14 @@ impl VirtioDevice for Gpu {
                         .run()
                     });
 
-            if let Err(e) = worker_result {
-                error!("failed to spawn virtio_gpu worker: {}", e);
-                return;
+            match worker_result {
+                Err(e) => {
+                    error!("failed to spawn virtio_gpu worker: {}", e);
+                    return;
+                }
+                Ok(join_handle) => {
+                    self.worker_thread = Some(join_handle);
+                }
             }
         }
     }