linux-kernel - [PATCH 4.14 6/6] Input: touchscreen - avoid bitwise vs logical OR warning

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Message-Id: <20211220122506.3631672-7-anders.roxell@linaro.org>
Date:   Mon, 20 Dec 2021 13:25:06 +0100
From:   Anders Roxell <anders.roxell@...aro.org>
To:     stable@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, woojung.huh@...rochip.com,
        UNGLinuxDriver@...rochip.com, davem@...emloft.net,
        netdev@...r.kernel.org, linux-usb@...r.kernel.org,
        clang-built-linux@...glegroups.com, ulli.kroll@...glemail.com,
        linux@...linux.org.uk, linux-arm-kernel@...ts.infradead.org,
        amitkarwar@...il.com, nishants@...vell.com, gbhat@...vell.com,
        huxinming820@...il.com, kvalo@...eaurora.org,
        linux-wireless@...r.kernel.org, rostedt@...dmis.org,
        mingo@...hat.com, dmitry.torokhov@...il.com,
        ndesaulniers@...gle.com, nathan@...nel.org,
        linux-input@...r.kernel.org,
        Anders Roxell <anders.roxell@...aro.org>
Subject: [PATCH 4.14 6/6] Input: touchscreen - avoid bitwise vs logical OR warning

From: Nathan Chancellor <nathan@...nel.org>

commit a02dcde595f7cbd240ccd64de96034ad91cffc40 upstream.

A new warning in clang points out a few places in this driver where a
bitwise OR is being used with boolean types:

drivers/input/touchscreen.c:81:17: warning: use of bitwise '|' with boolean operands [-Wbitwise-instead-of-logical]
        data_present = touchscreen_get_prop_u32(dev, "touchscreen-min-x",
                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This use of a bitwise OR is intentional, as bitwise operations do not
short circuit, which allows all the calls to touchscreen_get_prop_u32()
to happen so that the last parameter is initialized while coalescing the
results of the calls to make a decision after they are all evaluated.

To make this clearer to the compiler, use the '|=' operator to assign
the result of each touchscreen_get_prop_u32() call to data_present,
which keeps the meaning of the code the same but makes it obvious that
every one of these calls is expected to happen.

Signed-off-by: Nathan Chancellor <nathan@...nel.org>
Reported-by: Nick Desaulniers <ndesaulniers@...gle.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
Link: https://lore.kernel.org/r/20211014205757.3474635-1-nathan@kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
Signed-off-by: Anders Roxell <anders.roxell@...aro.org>
---
 drivers/input/touchscreen/of_touchscreen.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/input/touchscreen/of_touchscreen.c b/drivers/input/touchscreen/of_touchscreen.c
index 8d7f9c8f2771..db499ef6ccff 100644
--- a/drivers/input/touchscreen/of_touchscreen.c
+++ b/drivers/input/touchscreen/of_touchscreen.c
@@ -79,8 +79,8 @@ void touchscreen_parse_properties(struct input_dev *input, bool multitouch,
 	data_present = touchscreen_get_prop_u32(dev, "touchscreen-size-x",
 						input_abs_get_max(input,
 								  axis) + 1,
-						&maximum) |
-		       touchscreen_get_prop_u32(dev, "touchscreen-fuzz-x",
+						&maximum);
+	data_present |= touchscreen_get_prop_u32(dev, "touchscreen-fuzz-x",
 						input_abs_get_fuzz(input, axis),
 						&fuzz);
 	if (data_present)
@@ -90,8 +90,8 @@ void touchscreen_parse_properties(struct input_dev *input, bool multitouch,
 	data_present = touchscreen_get_prop_u32(dev, "touchscreen-size-y",
 						input_abs_get_max(input,
 								  axis) + 1,
-						&maximum) |
-		       touchscreen_get_prop_u32(dev, "touchscreen-fuzz-y",
+						&maximum);
+	data_present |= touchscreen_get_prop_u32(dev, "touchscreen-fuzz-y",
 						input_abs_get_fuzz(input, axis),
 						&fuzz);
 	if (data_present)
@@ -101,11 +101,11 @@ void touchscreen_parse_properties(struct input_dev *input, bool multitouch,
 	data_present = touchscreen_get_prop_u32(dev,
 						"touchscreen-max-pressure",
 						input_abs_get_max(input, axis),
-						&maximum) |
-		       touchscreen_get_prop_u32(dev,
-						"touchscreen-fuzz-pressure",
-						input_abs_get_fuzz(input, axis),
-						&fuzz);
+						&maximum);
+	data_present |= touchscreen_get_prop_u32(dev,
+						 "touchscreen-fuzz-pressure",
+						 input_abs_get_fuzz(input, axis),
+						 &fuzz);
 	if (data_present)
 		touchscreen_set_params(input, axis, maximum, fuzz);
 
-- 
2.34.1