From: Ben Gras <ben@minix3.org>
Date: Thu, 11 Dec 2008 13:42:37 +0000 (+0000)
Subject: fix race condition that can trigger 'enqueue already ready process' panic.
X-Git-Tag: v3.1.4~217
X-Git-Url: http://zhaoyanbai.com/repos/%22http:/www.isc.org/icons/man.dnssec-keyfromlabel.html?a=commitdiff_plain;h=a74132ec694aba570dd1d7cc6f31b33977571967;p=minix.git

fix race condition that can trigger 'enqueue already ready process' panic.
---

diff --git a/kernel/clock.c b/kernel/clock.c
index 80cc4c474..7124a8588 100755
--- a/kernel/clock.c
+++ b/kernel/clock.c
@@ -107,8 +107,12 @@ message *m_ptr;				/* pointer to request message */
    */ 
   if (prev_ptr->p_ticks_left <= 0 && priv(prev_ptr)->s_flags & PREEMPTIBLE) {
       if(prev_ptr->p_rts_flags == 0) {	/* if it was runnable .. */
-	lock_dequeue(prev_ptr);		/* take it off the queues */
-      	lock_enqueue(prev_ptr);		/* and reinsert it again */ 
+      lock;
+      {
+	dequeue(prev_ptr);		/* take it off the queues */
+      	enqueue(prev_ptr);		/* and reinsert it again */ 
+      }
+      unlock;
       } else {
 	kprintf("CLOCK: %d not runnable; flags: %x\n",
 		prev_ptr->p_endpoint, prev_ptr->p_rts_flags);