From c8e2123b6a217469f58f46af93be80fef2eaad2d Mon Sep 17 00:00:00 2001
From: Leandro Lupori <luporl@FreeBSD.org>
Date: Thu, 9 Aug 2018 14:04:51 +0000
Subject: [PATCH] [ppc] Fix kernel panic when using BOOTP_NFSROOT

On PowerPC (and possibly other architectures), that doesn't use
EARLY_AP_STARTUP, the config task queue may be used initialized.
This was observed while trying to mount the root fs from NFS, as
reported here: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=230168.

This patch has 2 main changes:
1- Perform a basic initialization of qgroup_config, similar to
what is done in taskqgroup_adjust, but simpler.
This makes qgroup_config ready to be used during NFS root mount.

2- When EARLY_AP_STARTUP is not used, call inm_init() and
in6m_init() right before SI_SUB_ROOT_CONF, because bootp needs
to send multicast packages to request an IP.

PR:		Bug 230168
Reported by:	sbruno
Reviewed by:	jhibbits, mmacy, sbruno
Approved by:	jhibbits
Differential Revision:	D16633
---
 sys/kern/subr_gtaskqueue.c | 18 ++++++++++++++++++
 sys/netinet/in_mcast.c     |  5 +++++
 sys/netinet6/in6_mcast.c   |  5 +++++
 3 files changed, 28 insertions(+)

diff --git a/sys/kern/subr_gtaskqueue.c b/sys/kern/subr_gtaskqueue.c
index 8a18ed24881..96dc530373a 100644
--- a/sys/kern/subr_gtaskqueue.c
+++ b/sys/kern/subr_gtaskqueue.c
@@ -857,6 +857,24 @@ taskqgroup_bind(struct taskqgroup *qgroup)
 	}
 }
 
+static void
+taskqgroup_config_init(void *arg)
+{
+	struct taskqgroup *qgroup = qgroup_config;
+	LIST_HEAD(, grouptask) gtask_head = LIST_HEAD_INITIALIZER(NULL);
+
+	LIST_SWAP(&gtask_head, &qgroup->tqg_queue[0].tgc_tasks,
+	    grouptask, gt_list);
+	qgroup->tqg_queue[0].tgc_cnt = 0;
+	taskqgroup_cpu_create(qgroup, 0, 0);
+
+	qgroup->tqg_cnt = 1;
+	qgroup->tqg_stride = 1;
+}
+
+SYSINIT(taskqgroup_config_init, SI_SUB_TASKQ, SI_ORDER_SECOND,
+	taskqgroup_config_init, NULL);
+
 static int
 _taskqgroup_adjust(struct taskqgroup *qgroup, int cnt, int stride)
 {
diff --git a/sys/netinet/in_mcast.c b/sys/netinet/in_mcast.c
index baff6f5db9d..f86133be0e3 100644
--- a/sys/netinet/in_mcast.c
+++ b/sys/netinet/in_mcast.c
@@ -231,8 +231,13 @@ static void inm_init(void)
 	taskqgroup_config_gtask_init(NULL, &free_gtask, inm_release_task, "inm release task");
 }
 
+#ifdef EARLY_AP_STARTUP
 SYSINIT(inm_init, SI_SUB_SMP + 1, SI_ORDER_FIRST,
 	inm_init, NULL);
+#else
+SYSINIT(inm_init, SI_SUB_ROOT_CONF - 1, SI_ORDER_FIRST,
+	inm_init, NULL);
+#endif
 
 
 void
diff --git a/sys/netinet6/in6_mcast.c b/sys/netinet6/in6_mcast.c
index 091d4d31b34..f7eb57effb0 100644
--- a/sys/netinet6/in6_mcast.c
+++ b/sys/netinet6/in6_mcast.c
@@ -562,8 +562,13 @@ static void in6m_init(void)
 	taskqgroup_config_gtask_init(NULL, &free_gtask, in6m_release_task, "in6m release task");
 }
 
+#ifdef EARLY_AP_STARTUP
 SYSINIT(in6m_init, SI_SUB_SMP + 1, SI_ORDER_FIRST,
 	in6m_init, NULL);
+#else
+SYSINIT(in6m_init, SI_SUB_ROOT_CONF - 1, SI_ORDER_SECOND,
+	in6m_init, NULL);
+#endif
 
 
 void