--- linux/include/linux/sched.h.orig	Mon Mar 13 16:49:12 2000
+++ linux/include/linux/sched.h	Mon Mar 13 17:37:32 2000
@@ -268,6 +268,7 @@
 					 */
 	struct exec_domain *exec_domain;
 	volatile long need_resched;
+	atomic_t may_preempt;
 
 	cycles_t avg_slice;
 	int lock_depth;		/* Lock depth. We can context switch in and out of holding a syscall kernel lock... */	
--- linux/include/asm-i386/uaccess.h.orig	Mon Mar 13 16:49:12 2000
+++ linux/include/asm-i386/uaccess.h	Mon Mar 13 17:38:30 2000
@@ -253,6 +253,7 @@
 #define __copy_user(to,from,size)					\
 do {									\
 	int __d0, __d1;							\
+	atomic_inc_local(&current->may_preempt);			\
 	__asm__ __volatile__(						\
 		"0:	rep; movsl\n"					\
 		"	movl %3,%0\n"					\
@@ -270,11 +271,13 @@
 		: "=&c"(size), "=&D" (__d0), "=&S" (__d1)		\
 		: "r"(size & 3), "0"(size / 4), "1"(to), "2"(from)	\
 		: "memory");						\
+	atomic_dec_local(&current->may_preempt);			\
 } while (0)
 
 #define __copy_user_zeroing(to,from,size)				\
 do {									\
 	int __d0, __d1;							\
+	atomic_inc_local(&current->may_preempt);			\
 	__asm__ __volatile__(						\
 		"0:	rep; movsl\n"					\
 		"	movl %3,%0\n"					\
@@ -298,6 +301,7 @@
 		: "=&c"(size), "=&D" (__d0), "=&S" (__d1)		\
 		: "r"(size & 3), "0"(size / 4), "1"(to), "2"(from)	\
 		: "memory");						\
+	atomic_dec_local(&current->may_preempt);			\
 } while (0)
 
 /* We let the __ versions of copy_from/to_user inline, because they're often
--- linux/include/asm-i386/atomic.h.orig	Mon Mar 13 17:35:08 2000
+++ linux/include/asm-i386/atomic.h	Mon Mar 13 17:36:36 2000
@@ -65,10 +65,30 @@
 		:"m" (__atomic_fool_gcc(v)));
 }
 
+/*
+ * This variant is an _IRQ-atomic_ (and compiler-barrier) increment,
+ * which is a simple but LOCK-less incl on x86.
+ */
+static __inline__ void atomic_inc_local(volatile atomic_t *v)
+{
+	__asm__ __volatile__(
+		"incl %0"
+		:"=m" (__atomic_fool_gcc(v))
+		:"m" (__atomic_fool_gcc(v)));
+}
+
 static __inline__ void atomic_dec(volatile atomic_t *v)
 {
 	__asm__ __volatile__(
 		LOCK "decl %0"
+		:"=m" (__atomic_fool_gcc(v))
+		:"m" (__atomic_fool_gcc(v)));
+}
+
+static __inline__ void atomic_dec_local(volatile atomic_t *v)
+{
+	__asm__ __volatile__(
+		"decl %0"
 		:"=m" (__atomic_fool_gcc(v))
 		:"m" (__atomic_fool_gcc(v)));
 }
--- linux/arch/i386/kernel/entry.S.orig	Mon Mar 13 16:49:12 2000
+++ linux/arch/i386/kernel/entry.S	Mon Mar 13 17:44:41 2000
@@ -76,7 +76,8 @@
 addr_limit	= 12
 exec_domain	= 16
 need_resched	= 20
-processor	= 56
+may_preempt	= 24
+processor	= 60
 
 ENOSYS = 38
 
@@ -280,6 +281,20 @@
 	movb CS(%esp),%al
 	testl $(VM_MASK | 3),%eax	# return to VM86 mode or non-supervisor?
 	jne ret_with_reschedule
+	cmpl $0, need_resched(%ebx)
+	jnz restore_all
+	cmpl $0, may_preempt(%ebx)
+	jz restore_all
+
+	/*
+	 * Preempt kernel-space, but only if we return to non-IRQ context:
+	 */
+	movl processor(%ebx), %eax
+	shll $5,%eax
+	movl SYMBOL_NAME(irq_stat)(,%eax), %edx
+	addl SYMBOL_NAME(irq_stat)+4(,%eax), %edx
+	jnz restore_all
+	call SYMBOL_NAME(schedule)
 	jmp restore_all
 
 	ALIGN