From: Daniel P. Berrangé <berrange@redhat.com>

When this commit was applied

  commit 9894dc0cdcc397ee5b26370bc53da6d360a363c2
  Author: Daniel P. Berrange <berrange@redhat.com>
  Date:   Tue Jan 19 11:14:29 2016 +0000

    char: convert from GIOChannel to QIOChannel

The tcp_chr_recv() function was changed to return QIO_CHANNEL_ERR_BLOCK
which corresonds to -2. As such the handling for EAGAIN was able to be
removed from tcp_chr_read(). Unfortunately in a later commit:

  commit b6572b4f97a7b126c7b24e165893ed9fe3d72e1f
  Author: Marc-André Lureau <marcandre.lureau@redhat.com>
  Date:   Fri Mar 11 18:55:24 2016 +0100

    char: translate from QIOChannel error to errno

The tcp_chr_recv() function was changed back to return -1, with errno
set to EAGAIN, without also re-addding support for this to tcp_chr_read()

Reported-by: Aleksey Kuleshov <rndfax@yandex.ru>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20180222121351.26191-1-berrange@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 chardev/char-socket.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index a220803c01..541fcf487d 100644
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -450,7 +450,7 @@ static gboolean tcp_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque)
         len = s->max_size;
     }
     size = tcp_chr_recv(chr, (void *)buf, len);
-    if (size == 0 || size == -1) {
+    if (size == 0 || (size == -1 && errno != EAGAIN)) {
         /* connection closed */
         tcp_chr_disconnect(chr);
     } else if (size > 0) {
-- 
2.14.3