When qemu_chr_fe_write() can not write to a backend and there
is no error, it might return '0' to let the caller retry.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 chardev/char-hub.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/chardev/char-hub.c b/chardev/char-hub.c
index d0967c22336..4bbde9fb033 100644
--- a/chardev/char-hub.c
+++ b/chardev/char-hub.c
@@ -65,7 +65,7 @@ static int hub_chr_write(Chardev *chr, const uint8_t *buf, int len)
             continue;
         }
         r = qemu_chr_fe_write(&d->backends[i].fe, buf, len);
-        if (r < 0) {
+        if (r <= 0) {
             if (errno == EAGAIN) {
                 /* Set index and expect to be called soon on watch wake up */
                 d->be_eagain_ind = i;
-- 
2.51.0