MFC r307518:

Fix device delete child function.

When detaching device trees parent devices must be detached prior to
detaching its children. This is because parent devices can have
pointers to the child devices in their softcs which are not
invalidated by device_delete_child(). This can cause use after free
issues and panic().

Device drivers implementing trees, must ensure its detach function
detaches or deletes all its children before returning.

While at it remove now redundant device_detach() calls before
device_delete_child() and device_delete_children(), mostly in
the USB controller drivers.

Tested by:		Jan Henrik Sylvester <me@janh.de>
Reviewed by:		jhb
Differential Revision:	https://reviews.freebsd.org/D8070

1 files changed, 0 insertions, 6 deletions

diff --git a/sys/arm/allwinner/a10_ehci.c b/sys/arm/allwinner/a10_ehci.c
index accf7f9..f754c9a 100644
--- a/sys/arm/allwinner/a10_ehci.c
+++ b/sys/arm/allwinner/a10_ehci.c
@@ -278,17 +278,11 @@ a10_ehci_detach(device_t self)
 	struct aw_ehci_softc *aw_sc = device_get_softc(self);
 	ehci_softc_t *sc = &aw_sc->sc;
 	const struct aw_ehci_conf *conf;
-	device_t bdev;
 	int err;
 	uint32_t reg_value = 0;
 
 	conf = USB_CONF(self);
 
-	if (sc->sc_bus.bdev) {
-		bdev = sc->sc_bus.bdev;
-		device_detach(bdev);
-		device_delete_child(self, bdev);
-	}
 	/* during module unload there are lots of children leftover */
 	device_delete_children(self);