xv6

commit 1133b215d8ce5f72d2252cf19b81fc29289d0b38
parent f70172129c94e4d53b56fc10a7d859679b581bd2
Author: rsc <rsc>
Date:   Thu,  7 Sep 2006 01:56:22 +0000

more defensive programming

Diffstat:
M
proc.c
 | 
5
++++-

1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/proc.c b/proc.c
@@ -371,7 +371,9 @@ proc_wait(void)
     havekids = 0;
     for(i = 0; i < NPROC; i++){
       p = &proc[i];
-      if(p->state != UNUSED && p->ppid == cp->pid){
+      if(p->state == UNUSED)
+        continue;
+      if(p->ppid == cp->pid){
         if(p->state == ZOMBIE){
           // Found one.
           kfree(p->mem, p->sz);
@@ -379,6 +381,7 @@ proc_wait(void)
           pid = p->pid;
           p->state = UNUSED;
           p->pid = 0;
+          p->ppid = 0;
           release(&proc_table_lock);
           return pid;
         }