linux-kernel - [PATCH v2 1/1] tty: Drop duplicate NULL check in TTY port functions

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Message-Id: <20220204153253.11006-1-andriy.shevchenko@linux.intel.com>
Date:   Fri,  4 Feb 2022 17:32:53 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>, linux-kernel@...r.kernel.org
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH v2 1/1] tty: Drop duplicate NULL check in TTY port functions

The free_page(addr), which becomes free_pages(addr, 0) checks addr against 0.
No need to repeat this check in the callers, i.e.  tty_port_free_xmit_buf()
and tty_port_destructor().

Note, INIT_KFIFO() is safe without that check, because it operates on
a separate member and doesn't rely on the FIFO itself to be allocated.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Acked-by: Jiri Slaby <jirislaby@...nel.org>
---
v2: updated note in commit message (Greg), added tag (Jiri)
 drivers/tty/tty_port.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index 4282895ede9e..880608a65773 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -240,11 +240,9 @@ EXPORT_SYMBOL(tty_port_alloc_xmit_buf);
 void tty_port_free_xmit_buf(struct tty_port *port)
 {
 	mutex_lock(&port->buf_mutex);
-	if (port->xmit_buf != NULL) {
-		free_page((unsigned long)port->xmit_buf);
-		port->xmit_buf = NULL;
-		INIT_KFIFO(port->xmit_fifo);
-	}
+	free_page((unsigned long)port->xmit_buf);
+	port->xmit_buf = NULL;
+	INIT_KFIFO(port->xmit_fifo);
 	mutex_unlock(&port->buf_mutex);
 }
 EXPORT_SYMBOL(tty_port_free_xmit_buf);
@@ -271,8 +269,7 @@ static void tty_port_destructor(struct kref *kref)
 	/* check if last port ref was dropped before tty release */
 	if (WARN_ON(port->itty))
 		return;
-	if (port->xmit_buf)
-		free_page((unsigned long)port->xmit_buf);
+	free_page((unsigned long)port->xmit_buf);
 	tty_port_destroy(port);
 	if (port->ops && port->ops->destruct)
 		port->ops->destruct(port);
-- 
2.34.1