| Message ID | 20190712090148.36582-1-arnd@arndb.de |
|---|---|
| State | Accepted |
| Commit | dfd6f9ad36368b8dbd5f5a2b2f0a4705ae69a323 |
| Headers | show |
| Series | acpi: fix false-positive -Wuninitialized warning | expand |
On Fri, Jul 12, 2019 at 11:01:21AM +0200, Arnd Bergmann wrote: > clang gets confused by an uninitialized variable in what looks > to it like a never executed code path: > > arch/x86/kernel/acpi/boot.c:618:13: error: variable 'polarity' is uninitialized when used here [-Werror,-Wuninitialized] > polarity = polarity ? ACPI_ACTIVE_LOW : ACPI_ACTIVE_HIGH; > ^~~~~~~~ > arch/x86/kernel/acpi/boot.c:606:32: note: initialize the variable 'polarity' to silence this warning > int rc, irq, trigger, polarity; > ^ > = 0 > arch/x86/kernel/acpi/boot.c:617:12: error: variable 'trigger' is uninitialized when used here [-Werror,-Wuninitialized] > trigger = trigger ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE; > ^~~~~~~ > arch/x86/kernel/acpi/boot.c:606:22: note: initialize the variable 'trigger' to silence this warning > int rc, irq, trigger, polarity; > ^ > = 0 > > This is unfortunately a design decision in clang and won't be fixed. > > Changing the acpi_get_override_irq() macro to an inline function > reliably avoids the issue. In this particular case it looks fine (perhaps in the future -1 shall be replaced with proper error code). Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> But in general it looks like clang obscures use of pretty well working macros. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > include/linux/acpi.h | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > index a95cce5e82e7..9426b9aaed86 100644 > --- a/include/linux/acpi.h > +++ b/include/linux/acpi.h > @@ -324,7 +324,10 @@ struct irq_domain *acpi_irq_create_hierarchy(unsigned int flags, > #ifdef CONFIG_X86_IO_APIC > extern int acpi_get_override_irq(u32 gsi, int *trigger, int *polarity); > #else > -#define acpi_get_override_irq(gsi, trigger, polarity) (-1) > +static inline int acpi_get_override_irq(u32 gsi, int *trigger, int *polarity) > +{ > + return -1; > +} > #endif > /* > * This function undoes the effect of one call to acpi_register_gsi(). > -- > 2.20.0 > -- With Best Regards, Andy Shevchenko
On Fri, Jul 12, 2019 at 11:01:21AM +0200, Arnd Bergmann wrote: > clang gets confused by an uninitialized variable in what looks > to it like a never executed code path: > > arch/x86/kernel/acpi/boot.c:618:13: error: variable 'polarity' is uninitialized when used here [-Werror,-Wuninitialized] > polarity = polarity ? ACPI_ACTIVE_LOW : ACPI_ACTIVE_HIGH; > ^~~~~~~~ > arch/x86/kernel/acpi/boot.c:606:32: note: initialize the variable 'polarity' to silence this warning > int rc, irq, trigger, polarity; > ^ > = 0 > arch/x86/kernel/acpi/boot.c:617:12: error: variable 'trigger' is uninitialized when used here [-Werror,-Wuninitialized] > trigger = trigger ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE; > ^~~~~~~ > arch/x86/kernel/acpi/boot.c:606:22: note: initialize the variable 'trigger' to silence this warning > int rc, irq, trigger, polarity; > ^ > = 0 > > This is unfortunately a design decision in clang and won't be fixed. > > Changing the acpi_get_override_irq() macro to an inline function > reliably avoids the issue. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
On Friday, July 12, 2019 11:01:21 AM CEST Arnd Bergmann wrote: > clang gets confused by an uninitialized variable in what looks > to it like a never executed code path: > > arch/x86/kernel/acpi/boot.c:618:13: error: variable 'polarity' is uninitialized when used here [-Werror,-Wuninitialized] > polarity = polarity ? ACPI_ACTIVE_LOW : ACPI_ACTIVE_HIGH; > ^~~~~~~~ > arch/x86/kernel/acpi/boot.c:606:32: note: initialize the variable 'polarity' to silence this warning > int rc, irq, trigger, polarity; > ^ > = 0 > arch/x86/kernel/acpi/boot.c:617:12: error: variable 'trigger' is uninitialized when used here [-Werror,-Wuninitialized] > trigger = trigger ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE; > ^~~~~~~ > arch/x86/kernel/acpi/boot.c:606:22: note: initialize the variable 'trigger' to silence this warning > int rc, irq, trigger, polarity; > ^ > = 0 > > This is unfortunately a design decision in clang and won't be fixed. > > Changing the acpi_get_override_irq() macro to an inline function > reliably avoids the issue. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > include/linux/acpi.h | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > index a95cce5e82e7..9426b9aaed86 100644 > --- a/include/linux/acpi.h > +++ b/include/linux/acpi.h > @@ -324,7 +324,10 @@ struct irq_domain *acpi_irq_create_hierarchy(unsigned int flags, > #ifdef CONFIG_X86_IO_APIC > extern int acpi_get_override_irq(u32 gsi, int *trigger, int *polarity); > #else > -#define acpi_get_override_irq(gsi, trigger, polarity) (-1) > +static inline int acpi_get_override_irq(u32 gsi, int *trigger, int *polarity) > +{ > + return -1; > +} > #endif > /* > * This function undoes the effect of one call to acpi_register_gsi(). > Applied, thanks!
diff --git a/include/linux/acpi.h b/include/linux/acpi.h index a95cce5e82e7..9426b9aaed86 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -324,7 +324,10 @@ struct irq_domain *acpi_irq_create_hierarchy(unsigned int flags, #ifdef CONFIG_X86_IO_APIC extern int acpi_get_override_irq(u32 gsi, int *trigger, int *polarity); #else -#define acpi_get_override_irq(gsi, trigger, polarity) (-1) +static inline int acpi_get_override_irq(u32 gsi, int *trigger, int *polarity) +{ + return -1; +} #endif /* * This function undoes the effect of one call to acpi_register_gsi().
clang gets confused by an uninitialized variable in what looks to it like a never executed code path: arch/x86/kernel/acpi/boot.c:618:13: error: variable 'polarity' is uninitialized when used here [-Werror,-Wuninitialized] polarity = polarity ? ACPI_ACTIVE_LOW : ACPI_ACTIVE_HIGH; ^~~~~~~~ arch/x86/kernel/acpi/boot.c:606:32: note: initialize the variable 'polarity' to silence this warning int rc, irq, trigger, polarity; ^ = 0 arch/x86/kernel/acpi/boot.c:617:12: error: variable 'trigger' is uninitialized when used here [-Werror,-Wuninitialized] trigger = trigger ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE; ^~~~~~~ arch/x86/kernel/acpi/boot.c:606:22: note: initialize the variable 'trigger' to silence this warning int rc, irq, trigger, polarity; ^ = 0 This is unfortunately a design decision in clang and won't be fixed. Changing the acpi_get_override_irq() macro to an inline function reliably avoids the issue. Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- include/linux/acpi.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) -- 2.20.0