| Message ID | 20190307155506.2993868-1-arnd@arndb.de (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | eefffb42f6659c9510105f3e4ebf2a8499d56936 |
| Headers | show |
| Series | [v3] spi: work around clang bug in SPI_BPW_RANGE_MASK() | expand |
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
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
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
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;
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(-)