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

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

details:   https://anonhg.NetBSD.org/src/rev/a37518299118
branches:  trunk
changeset: 834130:a37518299118
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sun Jul 29 02:06:11 2018 +0000

description:
Use callout_halt and usb_rem_task_wait in urtw(4).

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

diffstat:

 sys/dev/usb/if_urtw.c |  15 +++++++++++----
 1 files changed, 11 insertions(+), 4 deletions(-)

diffs (46 lines):

diff -r c628ec209c43 -r a37518299118 sys/dev/usb/if_urtw.c
--- a/sys/dev/usb/if_urtw.c     Sun Jul 29 02:02:04 2018 +0000
+++ b/sys/dev/usb/if_urtw.c     Sun Jul 29 02:06:11 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_urtw.c,v 1.15 2018/06/26 06:48:02 msaitoh Exp $     */
+/*     $NetBSD: if_urtw.c,v 1.16 2018/07/29 02:06:11 riastradh Exp $   */
 /*     $OpenBSD: if_urtw.c,v 1.39 2011/07/03 15:47:17 matthew Exp $    */
 
 /*-
@@ -19,7 +19,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_urtw.c,v 1.15 2018/06/26 06:48:02 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_urtw.c,v 1.16 2018/07/29 02:06:11 riastradh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_usb.h"
@@ -774,11 +774,13 @@
 
        sc->sc_dying = true;
 
+       callout_halt(&sc->scan_to, NULL);
+       callout_halt(&sc->sc_led_ch, NULL);
        callout_destroy(&sc->scan_to);
        callout_destroy(&sc->sc_led_ch);
 
-       usb_rem_task(sc->sc_udev, &sc->sc_task);
-       usb_rem_task(sc->sc_udev, &sc->sc_ledtask);
+       usb_rem_task_wait(sc->sc_udev, &sc->sc_task, USB_TASKQ_DRIVER);
+       usb_rem_task_wait(sc->sc_udev, &sc->sc_ledtask, USB_TASKQ_DRIVER);
 
        if (ifp->if_softc != NULL) {
                bpf_detach(ifp);
@@ -1042,6 +1044,11 @@
 {
        struct urtw_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->scan_to);