[PATCH 1/2] locking/qrwlock: include asm/byteorder.h as needed

[Arnd Bergmann]

Moving the qrwlock struct definition into a header file introduced
a subtle bug on all little-endian machines, where some files in some
configurations would see the fields in an incorrect order.  This was
found by building with an LTO enabled compiler that warns every time we
try to link together files with incompatible data structures.

A second patch changes linux/kconfig.h to always define the symbols,
but this seems to be the root cause of most of the issues, so I'd suggest
we do both.

On a current linux-next kernel, I verified that this header is
responsible for all type mismatches as a result from the endianess
confusion.

Cc: stable@xxxxxxxxxxxxxxx
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Fixes: e0d02285f16e ("locking/qrwlock: Use 'struct qrwlock' instead of 'struct __qrwlock'")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
 include/asm-generic/qrwlock_types.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/asm-generic/qrwlock_types.h b/include/asm-generic/qrwlock_types.h
index 137ecdd16daa..c36f1d5a2572 100644
--- a/include/asm-generic/qrwlock_types.h
+++ b/include/asm-generic/qrwlock_types.h
@@ -3,6 +3,7 @@
 #define __ASM_GENERIC_QRWLOCK_TYPES_H
 
 #include <linux/types.h>
+#include <asm/byteorder.h>
 #include <asm/spinlock_types.h>
 
 /*
-- 
2.9.0