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-rw-r--r--hw/char/cadence_uart.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/hw/char/cadence_uart.c b/hw/char/cadence_uart.c
index c856fc30b2..844542fd5a 100644
--- a/hw/char/cadence_uart.c
+++ b/hw/char/cadence_uart.c
@@ -288,8 +288,11 @@ static gboolean cadence_uart_xmit(GIOChannel *chan, GIOCondition cond,
}
ret = qemu_chr_fe_write(s->chr, s->tx_fifo, s->tx_count);
- s->tx_count -= ret;
- memmove(s->tx_fifo, s->tx_fifo + ret, s->tx_count);
+
+ if (ret >= 0) {
+ s->tx_count -= ret;
+ memmove(s->tx_fifo, s->tx_fifo + ret, s->tx_count);
+ }
if (s->tx_count) {
int r = qemu_chr_fe_add_watch(s->chr, G_IO_OUT|G_IO_HUP,