[PATCH] x86/hw_breakpoints: Return -EINVAL in default case in hw_breakpoint_arch_parse

[Nathan Chancellor]

When building with -Wsometimes-uninitialized, Clang warns:

arch/x86/kernel/hw_breakpoint.c:355:2: warning: variable 'align' is used
uninitialized whenever switch default is taken
[-Wsometimes-uninitialized]

It's not wrong but we can see that arch_build_bp_info will only ever
initialize hw->len to one of the specified switch cases. We can easily
silence Clang by just returning -EINVAL in the default case so that we
can never use align without initializing it first.

Link: https://github.com/ClangBuiltLinux/linux/issues/392
Suggested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
---
 arch/x86/kernel/hw_breakpoint.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index ff9bfd40429e..d73083021002 100644
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -354,6 +354,7 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
 #endif
 	default:
 		WARN_ON_ONCE(1);
+		return -EINVAL;
 	}
 
 	/*
-- 
2.21.0