serial: pch: move size check from pop_tx one level up

'count' is zero in the pop_tx()'s comparison against 'size'. So the 'if'
tries to find out if 'size' is negative or zero and returns in that
case. But it cannot be negative, due to previous (size < 0) check in the
caller: handle_tx().

So simply move this check from pop_tx() to handle_tx(). Now it's clear
that pop_tx() is called only if fifo_size is non-zero.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220503080613.27601-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index affe71f8b50c74fcc26266024080fa8419259d77..f872613a5e839b674045a941923044acbfdeac22 100644 (file)
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -791,7 +791,7 @@ static int pop_tx(struct eg20t_port *priv, int size)
        struct uart_port *port = &priv->port;
        struct circ_buf *xmit = &port->state->xmit;
 
-       if (uart_tx_stopped(port) || uart_circ_empty(xmit) || count >= size)
+       if (uart_tx_stopped(port) || uart_circ_empty(xmit))
                goto pop_tx_end;
 
        do {
@@ -895,14 +895,16 @@ static unsigned int handle_tx(struct eg20t_port *priv)
                tx_empty = 0;
                fifo_size--;
        }
+
        size = min(xmit->head - xmit->tail, fifo_size);
        if (size < 0)
                size = fifo_size;
-
-       tx_size = pop_tx(priv, size);
-       if (tx_size > 0) {
-               port->icount.tx += tx_size;
-               tx_empty = 0;
+       if (size) {
+               tx_size = pop_tx(priv, size);
+               if (tx_size > 0) {
+                       port->icount.tx += tx_size;
+                       tx_empty = 0;
+               }
        }
 
        priv->tx_empty = tx_empty;