Add support for ALQ(9) to be compiled and loaded as a kernel module.

Sponsored by:	FreeBSD Foundation
Reviewed by:	dwmalone, jeff, rpaulo, rwatson
Approved by:	kmacy (mentor)
MFC after:	1 month

1 files changed, 83 insertions, 1 deletions

diff --git a/sys/kern/kern_alq.c b/sys/kern/kern_alq.c
index a4ece79..20d4fee 100644
--- a/sys/kern/kern_alq.c
+++ b/sys/kern/kern_alq.c
@@ -1,7 +1,13 @@
 /*-
  * Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org>
+ * Copyright (c) 2008-2009, Lawrence Stewart <lstewart@freebsd.org>
+ * Copyright (c) 2009-2010, The FreeBSD Foundation
  * All rights reserved.
  *
+ * Portions of this software were developed at the Centre for Advanced
+ * Internet Architectures, Swinburne University of Technology, Melbourne,
+ * Australia by Lawrence Stewart under sponsorship from the FreeBSD Foundation.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
@@ -27,6 +33,8 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#include "opt_mac.h"
+
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/kernel.h>
@@ -180,9 +188,16 @@ ald_daemon(void)
 	ALD_LOCK();
 
 	for (;;) {
-		while ((alq = LIST_FIRST(&ald_active)) == NULL)
+		while ((alq = LIST_FIRST(&ald_active)) == NULL &&
+		    !ald_shutingdown)
 			msleep(&ald_active, &ald_mtx, PWAIT, "aldslp", 0);
 
+		/* Don't shutdown until all active ALQs are flushed. */
+		if (ald_shutingdown && alq == NULL) {
+			ALD_UNLOCK();
+			break;
+		}
+
 		ALQ_LOCK(alq);
 		ald_deactivate(alq);
 		ALD_UNLOCK();
@@ -192,6 +207,8 @@ ald_daemon(void)
 			wakeup(alq);
 		ALD_LOCK();
 	}
+
+	kproc_exit(0);
 }
 
 static void
@@ -200,14 +217,29 @@ ald_shutdown(void *arg, int howto)
 	struct alq *alq;
 
 	ALD_LOCK();
+
+	/* Ensure no new queues can be created. */
 	ald_shutingdown = 1;
 
+	/* Shutdown all ALQs prior to terminating the ald_daemon. */
 	while ((alq = LIST_FIRST(&ald_queues)) != NULL) {
 		LIST_REMOVE(alq, aq_link);
 		ALD_UNLOCK();
 		alq_shutdown(alq);
 		ALD_LOCK();
 	}
+
+	/* At this point, all ALQs are flushed and shutdown. */
+
+	/*
+	 * Wake ald_daemon so that it exits. It won't be able to do
+	 * anything until we msleep because we hold the ald_mtx.
+	 */
+	wakeup(&ald_active);
+
+	/* Wait for ald_daemon to exit. */
+	msleep(ald_proc, &ald_mtx, PWAIT, "aldslp", 0);
+
 	ALD_UNLOCK();
 }
 
@@ -510,3 +542,53 @@ alq_close(struct alq *alq)
 	free(alq->aq_entbuf, M_ALD);
 	free(alq, M_ALD);
 }
+
+static int
+alq_load_handler(module_t mod, int what, void *arg)
+{
+	int ret;
+	
+	ret = 0;
+
+	switch (what) {
+	case MOD_LOAD:
+	case MOD_SHUTDOWN:
+		break;
+
+	case MOD_QUIESCE:
+		ALD_LOCK();
+		/* Only allow unload if there are no open queues. */
+		if (LIST_FIRST(&ald_queues) == NULL) {
+			ald_shutingdown = 1;
+			ALD_UNLOCK();
+			ald_shutdown(NULL, 0);
+			mtx_destroy(&ald_mtx);
+		} else {
+			ALD_UNLOCK();
+			ret = EBUSY;
+		}
+		break;
+
+	case MOD_UNLOAD:
+		/* If MOD_QUIESCE failed we must fail here too. */
+		if (ald_shutingdown == 0)
+			ret = EBUSY;
+		break;
+
+	default:
+		ret = EINVAL;
+		break;
+	}
+
+	return (ret);
+}
+
+static moduledata_t alq_mod =
+{
+	"alq",
+	alq_load_handler,
+	NULL
+};
+
+DECLARE_MODULE(alq, alq_mod, SI_SUB_SMP, SI_ORDER_ANY);
+MODULE_VERSION(alq, 1);