[PATCH] [v3] spi: work around clang bug in SPI_BPW_RANGE_MASK()

[PATCH] [v3] spi: work around clang bug in SPI_BPW_RANGE_MASK()

[Arnd Bergmann]

Clang-8 evaluates both sides of a ?: expression to check for
valid arithmetic even in the side that is never taken. This
results in a build warning:

drivers/spi/spi-sh-msiof.c:1052:24: error: shift count >= width of type [-Werror,-Wshift-count-overflow]
        .bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32),
                              ^~~~~~~~~~~~~~~~~~~~~~~~~

Change the implementation to use the GENMASK() macro that does
what we want here but does not have a problem with the shift
count overflow.

Link: https://bugs.llvm.org/show_bug.cgi?id=38789
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v3: use GENMASK() instead of open-coding it
v2: add a code comment
---
 include/linux/spi/spi.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 662b336aa2e4..b27386450089 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -444,8 +444,7 @@ struct spi_controller {
 	/* bitmask of supported bits_per_word for transfers */
 	u32			bits_per_word_mask;
 #define SPI_BPW_MASK(bits) BIT((bits) - 1)
-#define SPI_BIT_MASK(bits) (((bits) == 32) ? ~0U : (BIT(bits) - 1))
-#define SPI_BPW_RANGE_MASK(min, max) (SPI_BIT_MASK(max) - SPI_BIT_MASK(min - 1))
+#define SPI_BPW_RANGE_MASK(min, max) GENMASK((min) - 1, (max) - 1)
 
 	/* limits on transfer speed */
 	u32			min_speed_hz;
-- 
2.20.0

Re: [PATCH] [v3] spi: work around clang bug in SPI_BPW_RANGE_MASK()

[Geert Uytterhoeven]

Hi Arnd,

On Thu, Mar 7, 2019 at 4:55 PM Arnd Bergmann <arnd@arndb.de> wrote:
> Clang-8 evaluates both sides of a ?: expression to check for
> valid arithmetic even in the side that is never taken. This
> results in a build warning:
>
> drivers/spi/spi-sh-msiof.c:1052:24: error: shift count >= width of type [-Werror,-Wshift-count-overflow]
>         .bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32),
>                               ^~~~~~~~~~~~~~~~~~~~~~~~~
>
> Change the implementation to use the GENMASK() macro that does
> what we want here but does not have a problem with the shift
> count overflow.
>
> Link: https://bugs.llvm.org/show_bug.cgi?id=38789
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Thanks for your patch!

> --- a/include/linux/spi/spi.h
> +++ b/include/linux/spi/spi.h
> @@ -444,8 +444,7 @@ struct spi_controller {
>         /* bitmask of supported bits_per_word for transfers */
>         u32                     bits_per_word_mask;
>  #define SPI_BPW_MASK(bits) BIT((bits) - 1)
> -#define SPI_BIT_MASK(bits) (((bits) == 32) ? ~0U : (BIT(bits) - 1))
> -#define SPI_BPW_RANGE_MASK(min, max) (SPI_BIT_MASK(max) - SPI_BIT_MASK(min - 1))
> +#define SPI_BPW_RANGE_MASK(min, max) GENMASK((min) - 1, (max) - 1)

Shouldn't that be GENMASK((max) - 1, (min) - 1)?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Applied "spi: work around clang bug in SPI_BPW_RANGE_MASK()" to the spi tree

[Mark Brown]

The patch

   spi: work around clang bug in SPI_BPW_RANGE_MASK()

has been applied to the spi tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

From eefffb42f6659c9510105f3e4ebf2a8499d56936 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Thu, 7 Mar 2019 16:54:21 +0100
Subject: [PATCH] spi: work around clang bug in SPI_BPW_RANGE_MASK()

Clang-8 evaluates both sides of a ?: expression to check for
valid arithmetic even in the side that is never taken. This
results in a build warning:

drivers/spi/spi-sh-msiof.c:1052:24: error: shift count >= width of type [-Werror,-Wshift-count-overflow]
        .bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32),
                              ^~~~~~~~~~~~~~~~~~~~~~~~~

Change the implementation to use the GENMASK() macro that does
what we want here but does not have a problem with the shift
count overflow.

Link: https://bugs.llvm.org/show_bug.cgi?id=38789
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 include/linux/spi/spi.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 662b336aa2e4..b27386450089 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -444,8 +444,7 @@ struct spi_controller {
 	/* bitmask of supported bits_per_word for transfers */
 	u32			bits_per_word_mask;
 #define SPI_BPW_MASK(bits) BIT((bits) - 1)
-#define SPI_BIT_MASK(bits) (((bits) == 32) ? ~0U : (BIT(bits) - 1))
-#define SPI_BPW_RANGE_MASK(min, max) (SPI_BIT_MASK(max) - SPI_BIT_MASK(min - 1))
+#define SPI_BPW_RANGE_MASK(min, max) GENMASK((min) - 1, (max) - 1)
 
 	/* limits on transfer speed */
 	u32			min_speed_hz;
-- 
2.20.1

Applied "spi: work around clang bug in SPI_BPW_RANGE_MASK()" to the spi tree

[Mark Brown]

The patch

   spi: work around clang bug in SPI_BPW_RANGE_MASK()

has been applied to the spi tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

From eefffb42f6659c9510105f3e4ebf2a8499d56936 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Thu, 7 Mar 2019 16:54:21 +0100
Subject: [PATCH] spi: work around clang bug in SPI_BPW_RANGE_MASK()

Clang-8 evaluates both sides of a ?: expression to check for
valid arithmetic even in the side that is never taken. This
results in a build warning:

drivers/spi/spi-sh-msiof.c:1052:24: error: shift count >= width of type [-Werror,-Wshift-count-overflow]
        .bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32),
                              ^~~~~~~~~~~~~~~~~~~~~~~~~

Change the implementation to use the GENMASK() macro that does
what we want here but does not have a problem with the shift
count overflow.

Link: https://bugs.llvm.org/show_bug.cgi?id=38789
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 include/linux/spi/spi.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 662b336aa2e4..b27386450089 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -444,8 +444,7 @@ struct spi_controller {
 	/* bitmask of supported bits_per_word for transfers */
 	u32			bits_per_word_mask;
 #define SPI_BPW_MASK(bits) BIT((bits) - 1)
-#define SPI_BIT_MASK(bits) (((bits) == 32) ? ~0U : (BIT(bits) - 1))
-#define SPI_BPW_RANGE_MASK(min, max) (SPI_BIT_MASK(max) - SPI_BIT_MASK(min - 1))
+#define SPI_BPW_RANGE_MASK(min, max) GENMASK((min) - 1, (max) - 1)
 
 	/* limits on transfer speed */
 	u32			min_speed_hz;
-- 
2.20.1

Re: Applied "spi: work around clang bug in SPI_BPW_RANGE_MASK()" to the spi tree

[Geert Uytterhoeven]

Hi Mark,

On Mon, Mar 11, 2019 at 6:26 PM Mark Brown <broonie@kernel.org> wrote:
> The patch
>
>    spi: work around clang bug in SPI_BPW_RANGE_MASK()
>
> has been applied to the spi tree at
>
>    https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git
>
> All being well this means that it will be integrated into the linux-next
> tree (usually sometime in the next 24 hours) and sent to Linus during
> the next merge window (or sooner if it is a bug fix), however if
> problems are discovered then the patch may be dropped or reverted.
>
> You may get further e-mails resulting from automated or manual testing
> and review of the tree, please engage with people reporting problems and
> send followup patches addressing any issues that are reported if needed.
>
> If any updates are required or you are submitting further changes they
> should be sent as incremental updates against current git, existing
> patches will not be replaced.
>
> Please add any relevant lists and maintainers to the CCs when replying
> to this mail.
>
> Thanks,
> Mark
>
> From eefffb42f6659c9510105f3e4ebf2a8499d56936 Mon Sep 17 00:00:00 2001
> From: Arnd Bergmann <arnd@arndb.de>
> Date: Thu, 7 Mar 2019 16:54:21 +0100
> Subject: [PATCH] spi: work around clang bug in SPI_BPW_RANGE_MASK()
>
> Clang-8 evaluates both sides of a ?: expression to check for
> valid arithmetic even in the side that is never taken. This
> results in a build warning:
>
> drivers/spi/spi-sh-msiof.c:1052:24: error: shift count >= width of type [-Werror,-Wshift-count-overflow]
>         .bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32),
>                               ^~~~~~~~~~~~~~~~~~~~~~~~~
>
> Change the implementation to use the GENMASK() macro that does
> what we want here but does not have a problem with the shift
> count overflow.
>
> Link: https://bugs.llvm.org/show_bug.cgi?id=38789
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
>  include/linux/spi/spi.h | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
> index 662b336aa2e4..b27386450089 100644
> --- a/include/linux/spi/spi.h
> +++ b/include/linux/spi/spi.h
> @@ -444,8 +444,7 @@ struct spi_controller {
>         /* bitmask of supported bits_per_word for transfers */
>         u32                     bits_per_word_mask;
>  #define SPI_BPW_MASK(bits) BIT((bits) - 1)
> -#define SPI_BIT_MASK(bits) (((bits) == 32) ? ~0U : (BIT(bits) - 1))
> -#define SPI_BPW_RANGE_MASK(min, max) (SPI_BIT_MASK(max) - SPI_BIT_MASK(min - 1))
> +#define SPI_BPW_RANGE_MASK(min, max) GENMASK((min) - 1, (max) - 1)

This is not correct: GENMASK() order is from msb to lsb.
So it should it:

+#define SPI_BPW_RANGE_MASK(min, max) GENMASK((max) - 1, (min) - 1)

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: Applied "spi: work around clang bug in SPI_BPW_RANGE_MASK()" to the spi tree

[Arnd Bergmann]

On Wed, Mar 13, 2019 at 8:15 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:

> > -#define SPI_BIT_MASK(bits) (((bits) == 32) ? ~0U : (BIT(bits) - 1))
> > -#define SPI_BPW_RANGE_MASK(min, max) (SPI_BIT_MASK(max) - SPI_BIT_MASK(min - 1))
> > +#define SPI_BPW_RANGE_MASK(min, max) GENMASK((min) - 1, (max) - 1)
>
> This is not correct: GENMASK() order is from msb to lsb.
> So it should it:
>
> +#define SPI_BPW_RANGE_MASK(min, max) GENMASK((max) - 1, (min) - 1)

Sorry about the mess, I've sent a fixup now.

       Arnd

Applied "spi: work around clang bug in SPI_BPW_RANGE_MASK()" to the spi tree

[Mark Brown]

The patch

   spi: work around clang bug in SPI_BPW_RANGE_MASK()

has been applied to the spi tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

From eefffb42f6659c9510105f3e4ebf2a8499d56936 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Thu, 7 Mar 2019 16:54:21 +0100
Subject: [PATCH] spi: work around clang bug in SPI_BPW_RANGE_MASK()

Clang-8 evaluates both sides of a ?: expression to check for
valid arithmetic even in the side that is never taken. This
results in a build warning:

drivers/spi/spi-sh-msiof.c:1052:24: error: shift count >= width of type [-Werror,-Wshift-count-overflow]
        .bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32),
                              ^~~~~~~~~~~~~~~~~~~~~~~~~

Change the implementation to use the GENMASK() macro that does
what we want here but does not have a problem with the shift
count overflow.

Link: https://bugs.llvm.org/show_bug.cgi?id=38789
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 include/linux/spi/spi.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 662b336aa2e4..b27386450089 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -444,8 +444,7 @@ struct spi_controller {
 	/* bitmask of supported bits_per_word for transfers */
 	u32			bits_per_word_mask;
 #define SPI_BPW_MASK(bits) BIT((bits) - 1)
-#define SPI_BIT_MASK(bits) (((bits) == 32) ? ~0U : (BIT(bits) - 1))
-#define SPI_BPW_RANGE_MASK(min, max) (SPI_BIT_MASK(max) - SPI_BIT_MASK(min - 1))
+#define SPI_BPW_RANGE_MASK(min, max) GENMASK((min) - 1, (max) - 1)
 
 	/* limits on transfer speed */
 	u32			min_speed_hz;
-- 
2.20.1