fix race in holding() check in acquire()

give cpu1 a TSS and gdt for when it enters scheduler()
and a pseudo proc[] entry for each cpu
cpu0 waits for each other cpu to start up
read() for files

1 files changed, 16 insertions, 12 deletions

diff --git a/spinlock.c b/spinlock.c
index bde6e46..5a0fd23 100644
--- a/spinlock.c
+++ b/spinlock.c
@@ -12,29 +12,31 @@
 
 extern int use_console_lock;
 
-int
-getcallerpc(void *v)
+void
+getcallerpcs(void *v, uint pcs[])
 {
-	return ((int*)v)[-1];
+  uint *ebp = (uint*)v - 2;
+  int i;
+  for(i = 0; i < 10 && ebp && ebp != (uint*)0xffffffff; ebp = (uint*)*ebp, i++){
+    pcs[i] = *(ebp + 1);
+  }
+  for( ; i < 10; i++)
+    pcs[i] = 0;
 }
 
 void
 acquire(struct spinlock * lock)
 {
-  if(holding(lock)){
-    extern use_console_lock;
-    use_console_lock = 0;
-    cprintf("lock %s pc %x\n", lock->name ? lock->name : "", lock->pc);
-		panic("acquire");
-  }
+  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->pc = getcallerpc(&lock);
-	lock->cpu = cpu();
+	getcallerpcs(&lock, lock->pcs);
+	lock->cpu = cpu() + 10;
         cpus[cpu()].lastacquire = lock;
 }
 
@@ -45,6 +47,8 @@ release(struct spinlock * lock)
 		panic("release");
 
         cpus[cpu()].lastrelease = lock;
+        lock->pcs[0] = 0;
+        lock->cpu = 0xffffffff;
 	cpuid(0, 0, 0, 0, 0);	// memory barrier
 	lock->locked = 0;
 	if(--cpus[cpu()].nlock == 0)
@@ -54,5 +58,5 @@ release(struct spinlock * lock)
 int
 holding(struct spinlock *lock)
 {
-	return lock->locked && lock->cpu == cpu();
+	return lock->locked && lock->cpu == cpu() + 10;
 }