From: Daniel P. Berrangé <berrange@redhat.com>
Date: Tue, 10 Jun 2025 12:37:08 +0000 (+0100)
Subject: net/socket: skip automatic zero-init of large array
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=751b0e79f1e0e7f88fad2fe2f22595ad03d78859;p=thirdparty%2Fqemu.git

net/socket: skip automatic zero-init of large array

The 'net_socket_send' method has a 68k byte array used for copying
data between guest and host. Skip the automatic zero-init of this
array to eliminate the performance overhead in the I/O hot path.

The 'buf1' 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>
Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Message-id: 20250610123709.835102-31-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---

diff --git a/net/socket.c b/net/socket.c
index 8e3702e1f3..784dda686f 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -157,7 +157,7 @@ static void net_socket_send(void *opaque)
     NetSocketState *s = opaque;
     int size;
     int ret;
-    uint8_t buf1[NET_BUFSIZE];
+    QEMU_UNINITIALIZED uint8_t buf1[NET_BUFSIZE];
     const uint8_t *buf;
 
     size = recv(s->fd, buf1, sizeof(buf1), 0);