linux-kernel - [PATCH] Staging: gdm724x: tty: Fix macro argument reuse that could cause side-effects.

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Date:   Fri, 16 Feb 2018 14:26:55 -0800
From:   Quytelda Kahja <quytelda@...alin.org>
To:     gregkh@...uxfoundation.org, gs051095@...il.com
Cc:     devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        Quytelda Kahja <quytelda@...alin.org>
Subject: [PATCH] Staging: gdm724x: tty: Fix macro argument reuse that could cause side-effects.

Fix a coding style warning from checkpatch.pl.  Use GNU extensions to create
references to the results of problem macro arguments when they are evaluated so
that they can be used safely multiple times.

Signed-off-by: Quytelda Kahja <quytelda@...alin.org>
---
 drivers/staging/gdm724x/gdm_tty.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/gdm724x/gdm_tty.c b/drivers/staging/gdm724x/gdm_tty.c
index fc7682c18f20..73d39fa86d10 100644
--- a/drivers/staging/gdm724x/gdm_tty.c
+++ b/drivers/staging/gdm724x/gdm_tty.c
@@ -37,14 +37,22 @@
 
 #define MUX_TX_MAX_SIZE 2048
 
-#define gdm_tty_send(n, d, l, i, c, b) (\
-	n->tty_dev->send_func(n->tty_dev->priv_dev, d, l, i, c, b))
-#define gdm_tty_recv(n, c) (\
-	n->tty_dev->recv_func(n->tty_dev->priv_dev, c))
-#define gdm_tty_send_control(n, r, v, d, l) (\
-	n->tty_dev->send_control(n->tty_dev->priv_dev, r, v, d, l))
-
-#define GDM_TTY_READY(gdm) (gdm && gdm->tty_dev && gdm->port.count)
+#define gdm_tty_send(n, d, l, i, c, b)					\
+	({ typeof(n) n_ = (n);						\
+		void *priv_dev = n_->tty_dev->priv_dev;			\
+		n_->tty_dev->send_func(priv_dev, d, l, i, c, b); })
+#define gdm_tty_recv(n, c)					\
+	({ typeof(n) n_ = (n);					\
+		void *priv_dev = n_->tty_dev->priv_dev;		\
+		n_->tty_dev->recv_func(priv_dev, c); })
+#define gdm_tty_send_control(n, r, v, d, l)				\
+	({ typeof(n) n_ = (n);						\
+		void *priv_dev = n_->tty_dev->priv_dev;			\
+		n_->tty_dev->send_control(priv_dev, r, v, d, l); })
+
+#define GDM_TTY_READY(gdm)						\
+	({ typeof(gdm) gdm_ = gdm;					\
+		gdm_ && gdm_->tty_dev && gdm_->port.count; })
 
 static struct tty_driver *gdm_driver[TTY_MAX_COUNT];
 static struct gdm *gdm_table[TTY_MAX_COUNT][GDM_TTY_MINOR];
-- 
2.16.1