From 65bd8e139a8368e987455a10ec59dd7b079b3af1 Mon Sep 17 00:00:00 2001
From: rsc <rsc>
Date: Sun, 16 Jul 2006 01:15:28 +0000
Subject: New scheduler.

Removed cli and sti stack in favor of tracking
number of locks held on each CPU and explicit
conditionals in spinlock.c.
---
 spinlock.c | 46 ++++++++++++++++++++--------------------------
 1 file changed, 20 insertions(+), 26 deletions(-)

(limited to 'spinlock.c')

diff --git a/spinlock.c b/spinlock.c
index 4c11064..aa11ad5 100644
--- a/spinlock.c
+++ b/spinlock.c
@@ -6,53 +6,47 @@
 #include "proc.h"
 #include "spinlock.h"
 
-#define DEBUG 0
+// Can't call cprintf from inside these routines,
+// because cprintf uses them itself.
+#define cprintf dont_use_cprintf
 
 extern int use_console_lock;
 
-int getcallerpc(void *v) {
-  return ((int*)v)[-1];
+int
+getcallerpc(void *v)
+{
+	return ((int*)v)[-1];
 }
 
 void
 acquire1(struct spinlock * lock, struct proc *cp)
 {
-  if(DEBUG) cprintf("cpu%d: acquiring at %x\n", cpu(), getcallerpc(&lock));
-
-  cli();
-  while ( cmpxchg(0, 1, &lock->locked) == 1 ) { ; }
-  lock->locker_pc = getcallerpc(&lock);
-
-  if(cp)
-    cp->locks += 1;
-
-  if(DEBUG) cprintf("cpu%d: acquired at %x\n", cpu(), getcallerpc(&lock));
+	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);
 }
 
 void
 release1(struct spinlock * lock, struct proc *cp)
 {
-
-  if(DEBUG) cprintf ("cpu%d: releasing at %x\n", cpu(), getcallerpc(&lock));
-
-  if(lock->locked != 1)
-    panic("release");
-
-  if(cp)
-    cp->locks -= 1;
-
-  cmpxchg(1, 0, &lock->locked);
-  sti();
+	cpuid(0, 0, 0, 0, 0);	// memory barrier
+	lock->locked = 0;
+	if(--cpus[cpu()].nlock == 0)
+		sti();
 }
 
 void
 acquire(struct spinlock *lock)
 {
-  acquire1(lock, curproc[cpu()]);
+	acquire1(lock, curproc[cpu()]);
 }
 
 void
 release(struct spinlock *lock)
 {
-  release1(lock, curproc[cpu()]);
+	release1(lock, curproc[cpu()]);
 }
+
-- 
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