Revise attach/detach resource cleanup

- Unconditionally call *_stop() if device is in the tree. This is to
  prevent callouts from happening after the device is gone. Checks for
  bus_child_present() should be added in the future to keep from touching
  potentially non-existent hardware in *_detach().  Found by iedowse@.
- Always check for and free miibus children, even if the device is not in
  the tree since some failure cases could have gotten here.
- Call ether_ifdetach() in the irq setup failure case
- ti(4), xl(4): move ifmedia_init() calls to the beginning of attach so
  that ifmedia_removeall() can be unconditionally called on detach. There
  is no way to detect whether ifmedia has been initialized without using
  a separate variable (as tl(4) does).
- Add comments to indicate assumptions of code path

1 files changed, 15 insertions, 6 deletions

diff --git a/sys/pci/if_pcn.c b/sys/pci/if_pcn.c
index 4462160..7fbd351 100644
--- a/sys/pci/if_pcn.c
+++ b/sys/pci/if_pcn.c
@@ -625,11 +625,13 @@ pcn_attach(dev)
 	 */
 	ether_ifattach(ifp, (u_int8_t *) eaddr);
 
+	/* Hook interrupt last to avoid having to lock softc */
 	error = bus_setup_intr(dev, sc->pcn_irq, INTR_TYPE_NET,
 	    pcn_intr, sc, &sc->pcn_intrhand);
 
 	if (error) {
 		printf("pcn%d: couldn't set up irq\n", unit);
+		ether_ifdetach(ifp);
 		goto fail;
 	}
 
@@ -640,6 +642,13 @@ fail:
 	return(error);
 }
 
+/*
+ * Shutdown hardware and free up resources. This can be called any
+ * time after the mutex has been initialized. It is called in both
+ * the error case in attach and the normal detach case so it needs
+ * to be careful about only freeing resources that have actually been
+ * allocated.
+ */
 static int
 pcn_detach(dev)
 	device_t		dev;
@@ -653,15 +662,15 @@ pcn_detach(dev)
 	KASSERT(mtx_initialized(&sc->pcn_mtx), ("pcn mutex not initialized"));
 	PCN_LOCK(sc);
 
+	/* These should only be active if attach succeeded */
 	if (device_is_alive(dev)) {
-		if (bus_child_present(dev)) {
-			pcn_reset(sc);
-			pcn_stop(sc);
-		}
+		pcn_reset(sc);
+		pcn_stop(sc);
 		ether_ifdetach(ifp);
-		device_delete_child(dev, sc->pcn_miibus);
-		bus_generic_detach(dev);
 	}
+	if (sc->pcn_miibus)
+		device_delete_child(dev, sc->pcn_miibus);
+	bus_generic_detach(dev);
 
 	if (sc->pcn_intrhand)
 		bus_teardown_intr(dev, sc->pcn_irq, sc->pcn_intrhand);