From: Leonardo Bras <leobras@redhat.com>
Date: Mon, 20 Jun 2022 05:39:43 +0000 (-0300)
Subject: QIOChannelSocket: Fix zero-copy send so socket flush works
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=4f5a09714c983a3471fd12e3c7f3196e95c650c1;p=qemu.git

QIOChannelSocket: Fix zero-copy send so socket flush works

Somewhere between v6 and v7 the of the zero-copy-send patchset a crucial
part of the flushing mechanism got missing: incrementing zero_copy_queued.

Without that, the flushing interface becomes a no-op, and there is no
guarantee the buffer is really sent.

This can go as bad as causing a corruption in RAM during migration.

Fixes: 2bc58ffc2926 ("QIOChannelSocket: Implement io_writev zero copy flag & io_flush for CONFIG_LINUX")
Reported-by: 徐闯 <xuchuangxclwt@bytedance.com>
Signed-off-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---

diff --git a/io/channel-socket.c b/io/channel-socket.c
index b8c13dba7c..4466bb1cd4 100644
--- a/io/channel-socket.c
+++ b/io/channel-socket.c
@@ -611,6 +611,11 @@ static ssize_t qio_channel_socket_writev(QIOChannel *ioc,
                          "Unable to write to socket");
         return -1;
     }
+
+    if (flags & QIO_CHANNEL_WRITE_FLAG_ZERO_COPY) {
+        sioc->zero_copy_queued++;
+    }
+
     return ret;
 }
 #else /* WIN32 */