chardev/char-socket: skip automatic zero-init of large array

The 'tcp_chr_read' method has a 4k byte array used for copying
data between the socket and device. Skip the automatic zero-init
of this array to eliminate the performance overhead in the I/O
hot path.

The 'buf' array will be fully initialized when reading data off
the network socket.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20250610123709.835102-7-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index e8dd2931dc282ce94c20d3facbaed919da3a9bf9..1e8313915b54050c4c46199af28966e884ad48c6 100644 (file)
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -497,7 +497,7 @@ static gboolean tcp_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque)
 {
     Chardev *chr = CHARDEV(opaque);
     SocketChardev *s = SOCKET_CHARDEV(opaque);
-    uint8_t buf[CHR_READ_BUF_LEN];
+    QEMU_UNINITIALIZED uint8_t buf[CHR_READ_BUF_LEN];
     int len, size;
 
     if ((s->state != TCP_CHARDEV_STATE_CONNECTED) ||