From f7be9273e522fd766ebfa0edf015b4dbf132bca4 Mon Sep 17 00:00:00 2001
From: Andrew Walbran <qwandor@google.com>
Date: Fri, 26 Jul 2024 13:37:03 +0100
Subject: [PATCH] Avoid allocating strings in Display implementation.

---
 src/device/sound.rs | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/src/device/sound.rs b/src/device/sound.rs
index f05dff17..31494b0a 100644
--- a/src/device/sound.rs
+++ b/src/device/sound.rs
@@ -1,7 +1,7 @@
 //! Driver for VirtIO Sound devices.
 
 use alloc::vec;
-use alloc::{boxed::Box, collections::BTreeMap, format, vec::Vec};
+use alloc::{boxed::Box, collections::BTreeMap, vec::Vec};
 use bitflags::bitflags;
 use core::{
     fmt::{self, Debug, Display, Formatter},
@@ -1655,16 +1655,19 @@ impl Display for VirtIOSndChmapInfo {
         } else {
             "OUTPUT"
         };
-        let mut positions = vec![];
-        for i in 0..self.channels as usize {
-            let position = format!("{:?}", ChannelPosition::from(self.positions[i]));
-            positions.push(position);
-        }
         write!(
             f,
-            "direction: {}, channels: {}, postions: {:?}",
-            direction, self.channels, positions
-        )
+            "direction: {}, channels: {}, postions: [",
+            direction, self.channels
+        )?;
+        for i in 0..usize::from(self.channels) {
+            if i != 0 {
+                write!(f, ", ")?;
+            }
+            write!(f, "{:?}", ChannelPosition::from(self.positions[i]))?;
+        }
+        write!(f, "]")?;
+        Ok(())
     }
 }