x86: Use correct byte-sized register constraint in __xchg_op()

x86-64 can access the low half of any register, but i386 can only do it with a subset of registers. 'r' causes compilation failures on i386, but 'q' expresses the constraint properly. Signed-off-by: Jeremy Fitzhardinge <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Reported-by: Leigh Scott <[email protected]> Tested-by: Thomas Reitmayr <[email protected]> Signed-off-by: H. Peter Anvin <[email protected]> Cc: <[email protected]> v3.3
jledet · Apr 6, 2012 · 2ca052a · 2ca052a
1 parent 46ed99d
commit 2ca052a
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/arch/x86/include/asm/cmpxchg.h b/arch/x86/include/asm/cmpxchg.h
@@ -43,7 +43,7 @@ extern void __add_wrong_size(void)
 		switch (sizeof(*(ptr))) {				\
 		case __X86_CASE_B:					\
 			asm volatile (lock #op "b %b0, %1\n"		\
-				      : "+r" (__ret), "+m" (*(ptr))	\
+				      : "+q" (__ret), "+m" (*(ptr))	\
 				      : : "memory", "cc");		\
 			break;						\
 		case __X86_CASE_W:					\