[src/trunk]: src/sys/dev/usb Use callout_halt and usb_rem_task_wait(4) in ura...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c628ec209c43
branches:  trunk
changeset: 834129:c628ec209c43
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sun Jul 29 02:02:04 2018 +0000

description:
Use callout_halt and usb_rem_task_wait(4) in ural(4) detach.

Also comment on sketchiness in ural_newstate that is beyond my scope
right now.

diffstat:

 sys/dev/usb/if_ural.c |  15 ++++++++++-----
 1 files changed, 10 insertions(+), 5 deletions(-)

diffs (43 lines):

diff -r 4d607485e1ac -r c628ec209c43 sys/dev/usb/if_ural.c
--- a/sys/dev/usb/if_ural.c     Sun Jul 29 02:01:54 2018 +0000
+++ b/sys/dev/usb/if_ural.c     Sun Jul 29 02:02:04 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_ural.c,v 1.55 2018/06/26 06:48:02 msaitoh Exp $ */
+/*     $NetBSD: if_ural.c,v 1.56 2018/07/29 02:02:04 riastradh Exp $ */
 /*     $FreeBSD: /repoman/r/ncvs/src/sys/dev/usb/if_ural.c,v 1.40 2006/06/02 23:14:40 sam Exp $        */
 
 /*-
@@ -24,7 +24,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_ural.c,v 1.55 2018/06/26 06:48:02 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_ural.c,v 1.56 2018/07/29 02:02:04 riastradh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_usb.h"
@@ -534,9 +534,9 @@
        s = splusb();
 
        ural_stop(ifp, 1);
-       usb_rem_task(sc->sc_udev, &sc->sc_task);
-       callout_stop(&sc->sc_scan_ch);
-       callout_stop(&sc->sc_amrr_ch);
+       callout_halt(&sc->sc_scan_ch, NULL);
+       callout_halt(&sc->sc_amrr_ch, NULL);
+       usb_rem_task_wait(sc->sc_udev, &sc->sc_task, USB_TASKQ_DRIVER);
 
        bpf_detach(ifp);
        ieee80211_ifdetach(ic);
@@ -784,6 +784,11 @@
 {
        struct ural_softc *sc = ic->ic_ifp->if_softc;
 
+       /*
+        * XXXSMP: This does not wait for the task, if it is in flight,
+        * to complete.  If this code works at all, it must rely on the
+        * kernel lock to serialize with the USB task thread.
+        */
        usb_rem_task(sc->sc_udev, &sc->sc_task);
        callout_stop(&sc->sc_scan_ch);
        callout_stop(&sc->sc_amrr_ch);