From 8a8be1b8c36e38f58f8ba3e425b6e701ad65abf3 Mon Sep 17 00:00:00 2001
From: rtm <rtm>
Date: Thu, 10 Aug 2006 02:07:10 +0000
Subject: low-level keyboard input (not hooked up to /dev yet) fix acquire() to
 cli() *before* incrementing nlock make T_SYSCALL a trap gate, not an
 interrupt gate sadly, various crashes if you hold down a keyboard key...

---
 spinlock.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

(limited to 'spinlock.c')

diff --git a/spinlock.c b/spinlock.c
index 5a0fd23..b1b4079 100644
--- a/spinlock.c
+++ b/spinlock.c
@@ -30,8 +30,10 @@ acquire(struct spinlock * lock)
   if(holding(lock))
     panic("acquire");
 
-	if(cpus[cpu()].nlock++ == 0)
-		cli();
+  if(cpus[cpu()].nlock == 0)
+    cli();
+  cpus[cpu()].nlock++;
+                
 	while(cmpxchg(0, 1, &lock->locked) == 1)
 		;
 	cpuid(0, 0, 0, 0, 0);	// memory barrier
@@ -53,6 +55,8 @@ release(struct spinlock * lock)
 	lock->locked = 0;
 	if(--cpus[cpu()].nlock == 0)
 		sti();
+        // xxx we may have just turned interrupts on during
+        // an interrupt, is that ok?
 }
 
 int
-- 
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