Linux-2.6.33.2/include/asm-generic/spinlock.h

#ifndef __ASM_GENERIC_SPINLOCK_H
#define __ASM_GENERIC_SPINLOCK_H
/*
 * You need to implement asm/spinlock.h for SMP support. The generic
 * version does not handle SMP.
 */
#ifdef CONFIG_SMP
#error need an architecture specific asm/spinlock.h
#endif

#endif /* __ASM_GENERIC_SPINLOCK_H */