[PATCH v2] staging: comedi: rewrite macro function with GNU extension typeof

From: Jules Irenge
Date: Mon Nov 04 2019 - 11:34:26 EST


Rewrite macro function with the GNU extension typeof
to remove a possible side-effects of MACRO argument reuse "x".
- Problem could rise if arguments have different types
and different use though.

Signed-off-by: Jules Irenge <jbi.octave@xxxxxxxxx>
---
v1 - had no full commit log message, with changes not intended to be in the patch
v2 - remove some changes not intended to be in this driver
include note of a potential problem
drivers/staging/comedi/comedi.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/comedi/comedi.h b/drivers/staging/comedi/comedi.h
index 09a940066c0e..a57691a2e8d8 100644
--- a/drivers/staging/comedi/comedi.h
+++ b/drivers/staging/comedi/comedi.h
@@ -1103,8 +1103,10 @@ enum ni_common_signal_names {

/* *** END GLOBALLY-NAMED NI TERMINALS/SIGNALS *** */

-#define NI_USUAL_PFI_SELECT(x) (((x) < 10) ? (0x1 + (x)) : (0xb + (x)))
-#define NI_USUAL_RTSI_SELECT(x) (((x) < 7) ? (0xb + (x)) : 0x1b)
+#define NI_USUAL_PFI_SELECT(x)\
+ ({typeof(x) x_ = (x); (x_ < 10) ? (0x1 + x_) : (0xb + x_); })
+#define NI_USUAL_RTSI_SELECT(x)\
+ ({typeof(x) x_ = (x); (x_ < 7) ? (0xb + x_) : 0x1b; })

/*
* mode bits for NI general-purpose counters, set with
--
2.23.0