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Subject[PATCH V2] arch/powerpc: use BUILD_BUG_ON_MSG() when detect unfit {cmp}xchg size
From: pan xinhui <xinhui.pan@linux.vnet.ibm.com>

__xchg_called_with_bad_pointer() can't tell us what codes use {cmp}xchg
in incorrect way. And no error will be reported until the link stage.
To fix such a kind of issues easily, we use BUILD_BUG_ON_MSG() here.

Signed-off-by: pan xinhui <xinhui.pan@linux.vnet.ibm.com>
---
change from V1:
use BUILD_BUG_ON_MSG to provide more build error messages.
---
arch/powerpc/include/asm/cmpxchg.h | 19 +++++--------------
1 file changed, 5 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/include/asm/cmpxchg.h b/arch/powerpc/include/asm/cmpxchg.h
index d1a8d93..730028b 100644
--- a/arch/powerpc/include/asm/cmpxchg.h
+++ b/arch/powerpc/include/asm/cmpxchg.h
@@ -5,6 +5,7 @@
#include <linux/compiler.h>
#include <asm/synch.h>
#include <asm/asm-compat.h>
+#include <linux/bug.h>

/*
* Atomic exchange
@@ -92,12 +93,6 @@ __xchg_u64_local(volatile void *p, unsigned long val)
}
#endif

-/*
- * This function doesn't exist, so you'll get a linker error
- * if something tries to do an invalid xchg().
- */
-extern void __xchg_called_with_bad_pointer(void);
-
static __always_inline unsigned long
__xchg(volatile void *ptr, unsigned long x, unsigned int size)
{
@@ -109,7 +104,7 @@ __xchg(volatile void *ptr, unsigned long x, unsigned int size)
return __xchg_u64(ptr, x);
#endif
}
- __xchg_called_with_bad_pointer();
+ BUILD_BUG_ON_MSG(1, "Unsupported size for __xchg");
return x;
}

@@ -124,7 +119,7 @@ __xchg_local(volatile void *ptr, unsigned long x, unsigned int size)
return __xchg_u64_local(ptr, x);
#endif
}
- __xchg_called_with_bad_pointer();
+ BUILD_BUG_ON_MSG(1, "Unsupported size for __xchg_local");
return x;
}
#define xchg(ptr,x) \
@@ -235,10 +230,6 @@ __cmpxchg_u64_local(volatile unsigned long *p, unsigned long old,
}
#endif

-/* This function doesn't exist, so you'll get a linker error
- if something tries to do an invalid cmpxchg(). */
-extern void __cmpxchg_called_with_bad_pointer(void);
-
static __always_inline unsigned long
__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new,
unsigned int size)
@@ -251,7 +242,7 @@ __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new,
return __cmpxchg_u64(ptr, old, new);
#endif
}
- __cmpxchg_called_with_bad_pointer();
+ BUILD_BUG_ON_MSG(1, "Unsupported size for __cmpxchg");
return old;
}

@@ -267,7 +258,7 @@ __cmpxchg_local(volatile void *ptr, unsigned long old, unsigned long new,
return __cmpxchg_u64_local(ptr, old, new);
#endif
}
- __cmpxchg_called_with_bad_pointer();
+ BUILD_BUG_ON_MSG(1, "Unsupported size for __cmpxchg_local");
return old;
}

--
2.5.0
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