On Thu, Oct 18, 2018 at 6:18 PM Borislav Petkov <bp@xxxxxxxxx> wrote:
>
> On Wed, Oct 17, 2018 at 09:40:53PM -0300, Leonardo Bras wrote:
> > The idea was to put it as default and fix all the shadowing warnings.
> > What do you think? I am open to suggestions.
>
> That's Masahiro's call. In the rest of the kernel, those warnings are behind
> the W=2 switch - i.e., not enabled by default.
It is not realistic to enable this warning option by default.
Even -Wshadow=local emits tons of warnings.
(More with -Wshadow)
The problem of this flag is,
it is false positive in macro expansions.
For example, I think the following is a legitimate case.
In file included from ./arch/arm64/include/asm/cputype.h:126:0,
from ./arch/arm64/include/asm/cache.h:19,
from ./include/linux/cache.h:6,
from ./include/linux/printk.h:9,
from ./include/linux/kernel.h:14,
from ./include/linux/bitmap.h:10,
from arch/arm64/kernel/fpsimd.c:20:
arch/arm64/kernel/fpsimd.c: In function ‘sve_kernel_enable’:
./arch/arm64/include/asm/sysreg.h:707:6: warning: declaration of
‘__val’ shadows a previous local [-Wshadow=compatible-local]
u64 __val; \
^
./arch/arm64/include/asm/sysreg.h:717:20: note: in definition of macro
‘write_sysreg’
u64 __val = (u64)(v); \
^
arch/arm64/kernel/fpsimd.c:713:15: note: in expansion of macro ‘read_sysreg’
write_sysreg(read_sysreg(CPACR_EL1) | CPACR_EL1_ZEN_EL1EN, CPACR_EL1);
^~~~~~~~~~~
./arch/arm64/include/asm/sysreg.h:717:6: note: shadowed declaration is here
u64 __val = (u64)(v); \
^
arch/arm64/kernel/fpsimd.c:713:2: note: in expansion of macro ‘write_sysreg’
write_sysreg(read_sysreg(CPACR_EL1) | CPACR_EL1_ZEN_EL1EN, CPACR_EL1);
^~~~~~~~~~~~
--
Best Regards
Masahiro Yamada
