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Subject[PATCH] acpi: fix false-positive -Wuninitialized warning
Date
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().
--
2.20.0
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