virtio-devices: Abort vhost-user client connect on kill_evt

Client connect retried for a full minute on every failure and did not
watch kill_evt for early exit, unlike reconnect, so teardown and
permanent connect errors both stalled for CONNECT_TIMEOUT.

Update the client path to watch kill_evt for early abort, fail
non-retryable errors immediately, and surface timeout with a dedicated
error.

Partially Fixes #8052

Signed-off-by: Chinmoy <daschinmoyy21@gmail.com>
Assisted-by: GLM 5.2

virtio-devices/src/vhost_user/blk.rs

@@ -63,7 +63,7 @@ impl Blk {
             &vu_cfg.socket,
             num_queues as u64,
             false,
-            None,
+            &exit_evt,
         )?;
 
         let (

virtio-devices/src/vhost_user/fs.rs

@@ -90,7 +90,7 @@ impl Fs {
 
         // Connect to the vhost-user socket.
         let mut vu =
-            VhostUserHandle::connect_vhost_user(false, path, num_queues as u64, false, None)?;
+            VhostUserHandle::connect_vhost_user(false, path, num_queues as u64, false, &exit_evt)?;
 
         let (
             avail_features,

virtio-devices/src/vhost_user/generic_vhost_user.rs

@@ -77,7 +77,7 @@ impl GenericVhostUser {
 
         // Connect to the vhost-user socket.
         let mut vu =
-            VhostUserHandle::connect_vhost_user(false, path, num_queues as u64, false, None)?;
+            VhostUserHandle::connect_vhost_user(false, path, num_queues as u64, false, &exit_evt)?;
 
         let (
             avail_features,

virtio-devices/src/vhost_user/mod.rs

@@ -179,6 +179,8 @@ pub enum Error {
     EpollWait(#[source] io::Error),
     #[error("Aborted vhost-user connect: kill event received")]
     ConnectKilled,
+    #[error("Timed out waiting for vhost-user connection")]
+    VhostUserConnectTimeout,
 }
 type Result<T> = result::Result<T, Error>;
 
@@ -329,7 +331,7 @@ impl<S: VhostUserFrontendReqHandler> VhostUserEpollHandler<S> {
             &self.socket_path,
             self.queues.len() as u64,
             true,
-            Some(&self.kill_evt),
+            &self.kill_evt,
         ) {
             Ok(vu) => vu,
             // Kill event fired during the connect retry loop; abandon the

virtio-devices/src/vhost_user/net.rs

@@ -93,7 +93,7 @@ impl Net {
             &vu_cfg.socket,
             num_queues as u64,
             false,
-            None,
+            &exit_evt,
         )?;
 
         let (

virtio-devices/src/vhost_user/vu_common_ctrl.rs

@@ -17,9 +17,13 @@ use vhost::vhost_user::message::{
     VhostUserProtocolFeatures, VhostUserVirtioFeatures,
 };
 use vhost::vhost_user::{
-    Frontend, FrontendReqHandler, VhostUserFrontend, VhostUserFrontendReqHandler,
+    Error as VhostUserError, Frontend, FrontendReqHandler, VhostUserFrontend,
+    VhostUserFrontendReqHandler,
+};
+use vhost::{
+    Error as VhostError, VhostBackend, VhostUserDirtyLogRegion, VhostUserMemoryRegionInfo,
+    VringConfigData,
 };
-use vhost::{VhostBackend, VhostUserDirtyLogRegion, VhostUserMemoryRegionInfo, VringConfigData};
 use virtio_queue::desc::RawDescriptor;
 use virtio_queue::{Queue, QueueT};
 use vm_memory::guest_memory::Error as MmapError;
@@ -381,7 +385,7 @@ impl VhostUserHandle {
         socket_path: &str,
         num_queues: u64,
         unlink_socket: bool,
-        kill_evt: Option<&EventFd>,
+        kill_evt: &EventFd,
     ) -> Result<Self> {
         if server {
             if unlink_socket {
@@ -427,15 +431,13 @@ impl VhostUserHandle {
                 )
                 .map_err(Error::EpollCtl)?;
 
-            if let Some(kill_evt) = kill_evt {
+            epoll
-                epoll
+                .ctl(
-                    .ctl(
+                    ControlOperation::Add,
-                        ControlOperation::Add,
+                    kill_evt.as_raw_fd(),
-                        kill_evt.as_raw_fd(),
+                    EpollEvent::new(EventSet::IN, ConnectEvent::Kill as u64),
-                        EpollEvent::new(EventSet::IN, ConnectEvent::Kill as u64),
+                )
-                    )
+                .map_err(Error::EpollCtl)?;
-                    .map_err(Error::EpollCtl)?;
-            }
 
             let start = Instant::now();
             let mut events = [EpollEvent::default(); 1];
@@ -457,13 +459,30 @@ impl VhostUserHandle {
                     Err(e) => e,
                 };
 
-                if start.elapsed() >= CONNECT_TIMEOUT {
+                let retryable = match &err {
+                    VhostError::VhostUserProtocol(VhostUserError::SocketConnect(io_err)) => {
+                        matches!(
+                            io_err.kind(),
+                            io::ErrorKind::NotFound
+                                | io::ErrorKind::Interrupted
+                                | io::ErrorKind::ConnectionRefused
+                        )
+                    }
+                    _ => false,
+                };
+
+                if !retryable {
                     error!(
-                        "Failed connecting the backend after trying for 1 minute for socket {socket_path}: {err:?}"
+                        "Failed connecting to vhost-user backend for socket {socket_path}: {err:?}"
                     );
                     return Err(Error::VhostUserConnect(err));
                 }
 
+                if start.elapsed() >= CONNECT_TIMEOUT {
+                    error!("Timed out waiting for vhost-user connection on socket {socket_path}");
+                    return Err(Error::VhostUserConnectTimeout);
+                }
+
                 loop {
                     match epoll.wait(-1, &mut events) {
                         Ok(_) => break,