1 files changed, 25 insertions, 6 deletions
diff --git a/spinlock.c b/spinlock.c
index 891f72c..61ae093 100644
--- a/spinlock.c
+++ b/spinlock.c
@@ -25,13 +25,10 @@ initlock(struct spinlock *lock, char *name)
 void
 acquire(struct spinlock *lock)
 {
+  splhi();
   if(holding(lock))
     panic("acquire");
 
-  if(cpus[cpu()].nlock == 0)
-    cli();
-  cpus[cpu()].nlock++;
-
   while(cmpxchg(0, 1, &lock->locked) == 1)
     ;
 
@@ -62,8 +59,7 @@ release(struct spinlock *lock)
   cpuid(0, 0, 0, 0, 0);  // memory barrier (see Ch 7, IA-32 manual vol 3)
 
   lock->locked = 0;
-  if(--cpus[cpu()].nlock == 0)
-    sti();
+  spllo();
 }
 
 // Record the current call stack in pcs[] by following the %ebp chain.
@@ -91,3 +87,26 @@ holding(struct spinlock *lock)
   return lock->locked && lock->cpu == cpu() + 10;
 }
 
+
+
+// XXX!
+// Better names?  Better functions?  
+
+void
+splhi(void)
+{
+  cli();
+  cpus[cpu()].nsplhi++;
+}
+
+void
+spllo(void)
+{
+  if(read_eflags()&FL_IF)
+    panic("spllo - interruptible");
+  if(--cpus[cpu()].nsplhi < 0)
+    panic("spllo");
+  if(cpus[cpu()].nsplhi == 0)
+    sti();
+}
+