linux-kernel - [PATCH 1/7] serial: pch: move size check from pop

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Message-Id: <20220503080613.27601-2-jslaby@suse.cz>
Date:   Tue,  3 May 2022 10:06:07 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     gregkh@...uxfoundation.org
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 1/7] 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@...e.cz>
---
 drivers/tty/serial/pch_uart.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index affe71f8b50c..f872613a5e83 100644
--- 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;
-- 
2.36.0