From a388d762285681826ff40231998cd31df94d2788 Mon Sep 17 00:00:00 2001
From: Bo Chen <chen.bo@intel.com>
Date: Wed, 19 Oct 2022 15:00:32 -0700
Subject: [PATCH] virtio-devices: console: Avoid using vector and direct
 indexing

The the number of queues and associated events is known and fixed. We
can define and use each of them explicitly and avoid using vector (and
hence direct indexing), which is cleaner and slightly more efficient.

Signed-off-by: Bo Chen <chen.bo@intel.com>
---
 virtio-devices/src/console.rs | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/virtio-devices/src/console.rs b/virtio-devices/src/console.rs
index ae2a7df6e..8f04267fc 100644
--- a/virtio-devices/src/console.rs
+++ b/virtio-devices/src/console.rs
@@ -77,7 +77,8 @@ unsafe impl ByteValued for VirtioConsoleConfig {}
 
 struct ConsoleEpollHandler {
     mem: GuestMemoryAtomic<GuestMemoryMmap>,
-    queues: Vec<Queue>,
+    input_queue: Queue,
+    output_queue: Queue,
     interrupt_cb: Arc<dyn VirtioInterrupt>,
     in_buffer: Arc<Mutex<VecDeque<u8>>>,
     resizer: Arc<ConsoleResizer>,
@@ -145,7 +146,8 @@ impl ConsoleEpollHandler {
     #[allow(clippy::too_many_arguments)]
     fn new(
         mem: GuestMemoryAtomic<GuestMemoryMmap>,
-        queues: Vec<Queue>,
+        input_queue: Queue,
+        output_queue: Queue,
         interrupt_cb: Arc<dyn VirtioInterrupt>,
         in_buffer: Arc<Mutex<VecDeque<u8>>>,
         resizer: Arc<ConsoleResizer>,
@@ -176,7 +178,8 @@ impl ConsoleEpollHandler {
 
         ConsoleEpollHandler {
             mem,
-            queues,
+            input_queue,
+            output_queue,
             interrupt_cb,
             in_buffer,
             resizer,
@@ -203,7 +206,7 @@ impl ConsoleEpollHandler {
      */
     fn process_input_queue(&mut self) -> bool {
         let mut in_buffer = self.in_buffer.lock().unwrap();
-        let recv_queue = &mut self.queues[0]; //receiveq
+        let recv_queue = &mut self.input_queue; //receiveq
         let mut used_descs = false;
 
         if in_buffer.is_empty() {
@@ -246,7 +249,7 @@ impl ConsoleEpollHandler {
      * to the referenced address.
      */
     fn process_output_queue(&mut self) -> bool {
-        let trans_queue = &mut self.queues[1]; //transmitq
+        let trans_queue = &mut self.output_queue; //transmitq
         let mut used_descs = false;
 
         while let Some(mut desc_chain) = trans_queue.pop_descriptor_chain(self.mem.memory()) {
@@ -714,17 +717,13 @@ impl VirtioDevice for Console {
         let (kill_evt, pause_evt) = self.common.dup_eventfds();
         let input_evt = EventFd::new(EFD_NONBLOCK).unwrap();
 
-        let mut virtqueues = Vec::new();
-        let (_, queue, queue_evt) = queues.remove(0);
-        virtqueues.push(queue);
-        let input_queue_evt = queue_evt;
-        let (_, queue, queue_evt) = queues.remove(0);
-        virtqueues.push(queue);
-        let output_queue_evt = queue_evt;
+        let (_, input_queue, input_queue_evt) = queues.remove(0);
+        let (_, output_queue, output_queue_evt) = queues.remove(0);
 
         let mut handler = ConsoleEpollHandler::new(
             mem,
-            virtqueues,
+            input_queue,
+            output_queue,
             interrupt_cb,
             self.in_buffer.clone(),
             Arc::clone(&self.resizer),