From: Andre Noll <maan@systemlinux.org>
Date: Mon, 31 Mar 2008 11:50:43 +0000 (+0200)
Subject: sched.c: Add checks for empty lists.
X-Git-Tag: v0.3.2~47
X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=commitdiff_plain;h=b0ab39b0d25bd4cd13afd33a72026b78f9e2f660;ds=sidebyside

sched.c: Add checks for empty lists.

This allows to call shed_shutdown() from the pre/post select hooks
of the tasks.
---

diff --git a/sched.c b/sched.c
index 90df5933..869c94c0 100644
--- a/sched.c
+++ b/sched.c
@@ -54,6 +54,14 @@ static void sched_preselect(struct sched *s)
 //		PARA_INFO_LOG("%s \n", t->status);
 		if (t->error >= 0)
 			continue;
+		/*
+		 * We have to check whether the list is empty because the call
+		 * to ->pre_select() might have called sched_shutdown(). In
+		 * this case t has been unregistered already, so we must not
+		 * unregister it again.
+		 */
+		if (list_empty(&pre_select_list))
+			return;
 		unregister_task(t);
 	}
 }
@@ -67,6 +75,9 @@ static void sched_post_select(struct sched *s)
 //		PARA_INFO_LOG("%s: %d\n", t->status, t->ret);
 		if (t->error >= 0)
 			continue;
+		/* nec., see sched_preselect() */
+		if (list_empty(&post_select_list))
+			return;
 		unregister_task(t);
 	}
 }
@@ -99,6 +110,8 @@ again:
 	s->timeout = s->default_timeout;
 	s->max_fileno = -1;
 	sched_preselect(s);
+	if (list_empty(&pre_select_list) && list_empty(&post_select_list))
+		return 0;
 	ret = para_select(s->max_fileno + 1, &s->rfds, &s->wfds, &s->timeout);
 	if (ret < 0)
 		return ret;