1 files changed, 13 insertions, 1 deletions

diff --git a/spinlock.c b/spinlock.c
index c0f236d..171afaf 100644
--- a/spinlock.c
+++ b/spinlock.c
@@ -21,20 +21,32 @@ getcallerpc(void *v)
 void
 acquire(struct spinlock * lock)
 {
+	if(holding(lock))
+		panic("acquire");
+
 	if(cpus[cpu()].nlock++ == 0)
 		cli();
 	while(cmpxchg(0, 1, &lock->locked) == 1)
 		;
 	cpuid(0, 0, 0, 0, 0);	// memory barrier
-	lock->locker_pc = getcallerpc(&lock);
+	lock->pc = getcallerpc(&lock);
+	lock->cpu = cpu();
 }
 
 void
 release(struct spinlock * lock)
 {
+	if(!holding(lock))
+		panic("release");
+
 	cpuid(0, 0, 0, 0, 0);	// memory barrier
 	lock->locked = 0;
 	if(--cpus[cpu()].nlock == 0)
 		sti();
 }
 
+int
+holding(struct spinlock *lock)
+{
+	return lock->locked && lock->cpu == cpu();
+}