fix possible race

13868496 · Nickolai Zeldovich · 7559ced5 · 13868496
--- a/sysfile.c
+++ b/sysfile.c
@@ -285,11 +285,14 @@ sys_open(void)
    if((ip = create(path, T_FILE, 0, 0)) == 0)
      return -1;
  } else {
+ retry:
    if((ip = namei(path)) == 0)
      return -1;
    ilock(ip, 0);
-    if(ip->type == 0)
+    if(ip->type == 0) {
-      panic("open");
+      iunlockput(ip);
+      goto retry;
+    }
    if(ip->type == T_DIR) {
      if (omode != O_RDONLY){
 	iunlockput(ip);