The athn(4) USB driver supports dual-band and uses the same broken pattern
as run(4). See http://marc.info/?l=openbsd-tech&m=143660130627359&w=2
Index: if_athn_usb.c
===================================================================
RCS file: /cvs/src/sys/dev/usb/if_athn_usb.c,v
retrieving revision 1.35
diff -u -p -r1.35 if_athn_usb.c
--- if_athn_usb.c 9 Jul 2015 13:48:54 -0000 1.35
+++ if_athn_usb.c 11 Jul 2015 08:07:22 -0000
@@ -570,16 +570,20 @@ athn_usb_task(void *arg)
struct athn_usb_softc *usc = arg;
struct athn_usb_host_cmd_ring *ring = &usc->cmdq;
struct athn_usb_host_cmd *cmd;
- int s;
+ int s, generation;
/* Process host commands. */
s = splusb();
+ generation = ring->generation;
while (ring->next != ring->cur) {
cmd = &ring->cmd[ring->next];
splx(s);
/* Invoke callback. */
cmd->cb(usc, cmd->data);
s = splusb();
+ /* Abort this task if interface was stopped meanwhile. */
+ if (generation != ring->generation)
+ break;
ring->queued--;
ring->next = (ring->next + 1) % ATHN_USB_HOST_CMD_RING_COUNT;
}
@@ -594,12 +598,12 @@ athn_usb_do_async(struct athn_usb_softc
struct athn_usb_host_cmd *cmd;
int s;
+ s = splusb();
if (ring->queued == ATHN_USB_HOST_CMD_RING_COUNT) {
printf("%s: host cmd queue overrun\n", usc->usb_dev.dv_xname);
+ splx(s);
return; /* XXX */
}
-
- s = splusb();
cmd = &ring->cmd[ring->cur];
cmd->cb = cb;
KASSERT(len <= sizeof(cmd->data));
@@ -2365,6 +2369,10 @@ athn_usb_stop(struct ifnet *ifp)
ifp->if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);
s = splusb();
+
+ /* Abort athn_usb_task thread. */
+ usc->cmdq.generation++;
+
ieee80211_new_state(ic, IEEE80211_S_INIT, -1);
/* Wait for all async commands to complete. */
Index: if_athn_usb.h
===================================================================
RCS file: /cvs/src/sys/dev/usb/if_athn_usb.h,v
retrieving revision 1.6
diff -u -p -r1.6 if_athn_usb.h
--- if_athn_usb.h 2 Mar 2015 14:46:02 -0000 1.6
+++ if_athn_usb.h 11 Jul 2015 08:04:25 -0000
@@ -412,6 +412,7 @@ struct athn_usb_host_cmd_ring {
int cur;
int next;
int queued;
+ int generation;
};
struct athn_usb_softc {
