git: 19866d1a162f - stable/13 - ofwbus: only allow unit number zero

The branch stable/13 has been updated by mhorne:

URL: https://cgit.FreeBSD.org/src/commit/?id=19866d1a162fca492ca5a7776d209d1ea4ae565e

commit 19866d1a162fca492ca5a7776d209d1ea4ae565e
Author:     Mitchell Horne <mhorne@FreeBSD.org>
AuthorDate: 2023-02-13 17:44:03 +0000
Commit:     Mitchell Horne <mhorne@FreeBSD.org>
CommitDate: 2023-04-17 16:54:04 +0000

    ofwbus: only allow unit number zero
    
    ofwbus has always been the root of attachment for OFW/FDT platforms. It
    may have simplebus children, but we expect only one instance of the
    ofwbus driver, added directly by nexus. We may as well ensure this
    remains the case.
    
    Reviewed by:    jhb
    MFC after:      2 weeks
    Differential Revision:  https://reviews.freebsd.org/D38493
    
    (cherry picked from commit afca197f5240ce2c2c7abfe5c9fbc50ba55f178b)
---
 sys/dev/ofw/ofwbus.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/sys/dev/ofw/ofwbus.c b/sys/dev/ofw/ofwbus.c
index 7660be8cec39..c97fd41bb683 100644
--- a/sys/dev/ofw/ofwbus.c
+++ b/sys/dev/ofw/ofwbus.c
@@ -98,6 +98,11 @@ ofwbus_probe(device_t dev)
 	if (OF_peer(0) == 0)
 		return (ENXIO);
 
+	/* Only one instance of ofwbus. */
+	if (device_get_unit(dev) != 0)
+		panic("ofwbus added with non-zero unit number: %d\n",
+		    device_get_unit(dev));
+
 	device_set_desc(dev, "Open Firmware Device Tree");
 	return (BUS_PROBE_NOWILDCARD);
 }