diff mbox series

[4.19,6/6] Input: touchscreen - avoid bitwise vs logical OR warning

Message ID 20211217144119.2538175-7-anders.roxell@linaro.org (mailing list archive)
State Superseded
Headers show
Series fix warning and errors on arm built with clang | expand

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Context Check Description
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Commit Message

Anders Roxell Dec. 17, 2021, 2:41 p.m. UTC
From: Nathan Chancellor <nathan@kernel.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@kernel.org>
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20211014205757.3474635-1-nathan@kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 drivers/input/touchscreen/of_touchscreen.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

Comments

Greg KH Dec. 20, 2021, 10:59 a.m. UTC | #1
On Fri, Dec 17, 2021 at 03:41:19PM +0100, Anders Roxell wrote:
> From: Nathan Chancellor <nathan@kernel.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@kernel.org>
> Reported-by: Nick Desaulniers <ndesaulniers@google.com>
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> Link: https://lore.kernel.org/r/20211014205757.3474635-1-nathan@kernel.org
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
> ---
>  drivers/input/touchscreen/of_touchscreen.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)

Also needed in 5.10.y and 5.4.y.

Please be more careful next time.
Anders Roxell Dec. 21, 2021, 12:24 p.m. UTC | #2
On Mon, 20 Dec 2021 at 11:59, Greg KH <greg@kroah.com> wrote:
>
> On Fri, Dec 17, 2021 at 03:41:19PM +0100, Anders Roxell wrote:
> > From: Nathan Chancellor <nathan@kernel.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@kernel.org>
> > Reported-by: Nick Desaulniers <ndesaulniers@google.com>
> > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> > Link: https://lore.kernel.org/r/20211014205757.3474635-1-nathan@kernel.org
> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> > Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
> > ---
> >  drivers/input/touchscreen/of_touchscreen.c | 18 +++++++++---------
> >  1 file changed, 9 insertions(+), 9 deletions(-)
>
> Also needed in 5.10.y and 5.4.y.
>
> Please be more careful next time.

Yes I will, I'm sorry.

Cheers,
Anders
diff mbox series

Patch

diff --git a/drivers/input/touchscreen/of_touchscreen.c b/drivers/input/touchscreen/of_touchscreen.c
index 9642f103b726..b9baad7d34a7 100644
--- a/drivers/input/touchscreen/of_touchscreen.c
+++ b/drivers/input/touchscreen/of_touchscreen.c
@@ -80,8 +80,8 @@  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)
@@ -91,8 +91,8 @@  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)
@@ -102,11 +102,11 @@  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);