"kernel_locked()" needs <linux/smp_lock.h>.

So make sure to include it in <asm-i386/hardirq.h> when needed
(ie for the CONFIG_PREEMPT case).

include/asm-i386/hardirq.h

@@ -77,6 +77,7 @@ typedef struct {
 #define nmi_exit()		(preempt_count() -= HARDIRQ_OFFSET)
 
 #ifdef CONFIG_PREEMPT
+# include <linux/smp_lock.h>
 # define in_atomic()	((preempt_count() & ~PREEMPT_ACTIVE) != kernel_locked())
 # define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
 #else