From 5edb8fd098c2f392702a7b07bda664f1acf4b350 Mon Sep 17 00:00:00 2001
From: Andre Noll <maan@systemlinux.org>
Date: Sun, 8 Jul 2012 18:57:24 +0000
Subject: [PATCH] sched: Replace sched_shutdown() by task_notify_all().

sched_shutdown() was mis-designed from the beginning as the registered
tasks have no chance to clean up. Using task notifiers allows to
replace the single caller of sched_shutdown().
---
 afs.c   | 10 ++++++++--
 sched.c | 50 +++++++++++++++++++-------------------------------
 sched.h |  2 +-
 3 files changed, 28 insertions(+), 34 deletions(-)

diff --git a/afs.c b/afs.c
index f1e28f14..1f3fafac 100644
--- a/afs.c
+++ b/afs.c
@@ -744,7 +744,7 @@ static void afs_signal_post_select(struct sched *s, struct task *t)
 	}
 	PARA_EMERG_LOG("terminating on signal %d\n", signum);
 shutdown:
-	sched_shutdown(s);
+	task_notify_all(s, E_AFS_SIGNAL);
 	t->error = -E_AFS_SIGNAL;
 }
 
@@ -921,10 +921,16 @@ static void command_post_select(struct sched *s, struct task *t)
 	struct afs_client *client, *tmp;
 	int fd, ret;
 
+	ret = task_get_notification(t);
+	if (ret < 0) {
+		t->error = ret;
+		return;
+	}
 	ret = execute_server_command(&s->rfds);
 	if (ret < 0) {
 		PARA_EMERG_LOG("%s\n", para_strerror(-ret));
-		sched_shutdown(s);
+		task_notify_all(s, -ret);
+		t->error = ret;
 		return;
 	}
 	/* Check the list of connected clients. */
diff --git a/sched.c b/sched.c
index e67579b3..ae82b233 100644
--- a/sched.c
+++ b/sched.c
@@ -98,14 +98,6 @@ static void sched_post_select(struct sched *s)
 		t->notification = 0;
 		if (t->error >= 0)
 			continue;
-		/*
-		 * We have to check whether the list is empty because the call
-		 * to ->post_select() might have called sched_shutdown(). In
-		 * this case t has been unregistered already, so we must not
-		 * unregister it again.
-		 */
-		if (list_empty(&s->post_select_list))
-			return;
 		unregister_task(t);
 	}
 }
@@ -195,29 +187,6 @@ void register_task(struct sched *s, struct task *t)
 	}
 }
 
-/**
- * Unregister all tasks.
- *
- * \param s The scheduler instance to shut down.
- *
- * This will cause \a schedule() to return immediately because both the
- * \a pre_select_list and the \a post_select_list are empty. This function
- * must be called from the post_select (rather than the pre_select) method.
- */
-void sched_shutdown(struct sched *s)
-{
-	struct task *t, *tmp;
-
-	list_for_each_entry_safe(t, tmp, &s->pre_select_list, pre_select_node) {
-		t->error = -E_SCHED_SHUTDOWN;
-		unregister_task(t);
-	}
-	list_for_each_entry_safe(t, tmp, &s->post_select_list, post_select_node) {
-		t->error = -E_SCHED_SHUTDOWN;
-		unregister_task(t);
-	}
-}
-
 /**
  * Get the list of all registered tasks.
  *
@@ -295,6 +264,25 @@ int task_get_notification(struct task *t)
 	return t->notification;
 }
 
+/**
+ * Set the notification value of all tasks of a scheduler instance.
+ *
+ * \param s The scheduler instance whose tasks should be notified.
+ * \param err A positive error code.
+ *
+ * This simply iterates over all existing tasks of \a s and sets each
+ * task's notification value to \p -err.
+ */
+void task_notify_all(struct sched *s, int err)
+{
+	struct task *t;
+
+	list_for_each_entry(t, &s->pre_select_list, pre_select_node)
+		task_notify(t, err);
+	list_for_each_entry(t, &s->post_select_list, post_select_node)
+		task_notify(t, err);
+}
+
 /**
  * Set the select timeout to the minimal possible value.
  *
diff --git a/sched.h b/sched.h
index 9d4d52e2..74c3fc65 100644
--- a/sched.h
+++ b/sched.h
@@ -84,7 +84,7 @@ void register_task(struct sched *s, struct task *t);
 int schedule(struct sched *s);
 char *get_task_list(struct sched *s);
 void task_notify(struct task *t, int err);
-void sched_shutdown(struct sched *s);
+void task_notify_all(struct sched *s, int err);
 int task_get_notification(struct task *t);
 void sched_min_delay(struct sched *s);
 void sched_request_timeout(struct timeval *to, struct sched *s);
-- 
2.39.5