Fix scanning with athn(4) USB devices.

The driver artificially limited the number of slots for nodes in its net80211
node cache to 8, the rationale being the device firmware can only handle 8
associated nodes at a time. But that's not a good reason to only cache 8 of
potentially many APs in the area.

Instead of crippling upper layer data structures, impose the limit locally
by raising an error if more than 8 nodes are trying to associate (which can
only happen in hostap mode, and hostap mode seems to be broken anyway).
This matches what Linux ath9k does.

Also, use a USB-specific scan timeout callback to we can do USB refcounting
while scanning.

ok mpi@

2 files changed, 36 insertions, 6 deletions

diff --git a/sys/dev/usb/if_athn_usb.c b/sys/dev/usb/if_athn_usb.c
index de66c8040fb..b20c3db7d23 100644
--- a/sys/dev/usb/if_athn_usb.c
+++ b/sys/dev/usb/if_athn_usb.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_athn_usb.c,v 1.28 2015/03/02 13:13:51 stsp Exp $	*/
+/*	$OpenBSD: if_athn_usb.c,v 1.29 2015/03/02 13:47:08 stsp Exp $	*/
 
 /*-
  * Copyright (c) 2011 Damien Bergamini <damien.bergamini@free.fr>
@@ -126,6 +126,7 @@ uint32_t	athn_usb_read(struct athn_softc *, uint32_t);
 void		athn_usb_write(struct athn_softc *, uint32_t, uint32_t);
 void		athn_usb_write_barrier(struct athn_softc *);
 int		athn_usb_media_change(struct ifnet *);
+void		athn_usb_next_scan(void *);
 int		athn_usb_newstate(struct ieee80211com *, enum ieee80211_state,
 		    int);
 void		athn_usb_newstate_cb(struct athn_usb_softc *, void *);
@@ -350,10 +351,7 @@ athn_usb_attachhook(void *xsc)
 #endif
 	ic->ic_newstate = athn_usb_newstate;
 	ic->ic_media.ifm_change = athn_usb_media_change;
-
-	/* Firmware cannot handle more than 8 STAs. */
-	if (ic->ic_max_nnodes > AR_USB_MAX_STA)
-		ic->ic_max_nnodes = AR_USB_MAX_STA;
+	timeout_set(&sc->scan_to, athn_usb_next_scan, usc);
 
 	ops->rx_enable = athn_usb_rx_enable;
 	splx(s);
@@ -984,6 +982,27 @@ athn_usb_media_change(struct ifnet *ifp)
 	return (error);
 }
 
+void
+athn_usb_next_scan(void *arg)
+{
+	struct athn_usb_softc *usc = arg;
+	struct athn_softc *sc = &usc->sc_sc;
+	struct ieee80211com *ic = &sc->sc_ic;
+	int s;
+
+	if (usbd_is_dying(usc->sc_udev))
+		return;
+
+	usbd_ref_incr(usc->sc_udev);
+
+	s = splnet();
+	if (ic->ic_state == IEEE80211_S_SCAN)
+		ieee80211_next_scan(&ic->ic_if);
+	splx(s);
+
+	usbd_ref_decr(usc->sc_udev);
+}
+
 int
 athn_usb_newstate(struct ieee80211com *ic, enum ieee80211_state nstate,
     int arg)
@@ -1124,6 +1143,7 @@ athn_usb_node_leave_cb(struct athn_usb_softc *usc, void *arg)
 
 	(void)athn_usb_wmi_xcmd(usc, AR_WMI_CMD_NODE_REMOVE,
 	    &sta_index, sizeof(sta_index), NULL);
+	usc->nnodes--;
 }
 
 int
@@ -1191,6 +1211,10 @@ athn_usb_create_node(struct athn_usb_softc *usc, struct ieee80211_node *ni)
 	struct ar_htc_target_rate rate;
 	int error;
 
+	/* Firmware cannot handle more than 8 STAs. */
+	if (usc->nnodes > AR_USB_MAX_STA)
+		return ENOBUFS;
+
 	an->sta_index = IEEE80211_AID(ni->ni_associd);
 
 	/* Create node entry on target. */
@@ -1207,6 +1231,7 @@ athn_usb_create_node(struct athn_usb_softc *usc, struct ieee80211_node *ni)
 	    &sta, sizeof(sta), NULL);
 	if (error != 0)
 		return (error);
+	usc->nnodes++;
 
 	/* Setup supported rates. */
 	memset(&rate, 0, sizeof(rate));
@@ -2240,6 +2265,7 @@ athn_usb_init(struct ifnet *ifp)
 	    &sta, sizeof(sta), NULL);
 	if (error != 0)
 		goto fail;
+	usc->nnodes++;
 
 	/* Update target capabilities. */
 	memset(&hic, 0, sizeof(hic));
@@ -2322,6 +2348,7 @@ athn_usb_stop(struct ifnet *ifp)
 	sta_index = 0;
 	(void)athn_usb_wmi_xcmd(usc, AR_WMI_CMD_NODE_REMOVE,
 	    &sta_index, sizeof(sta_index), NULL);
+	usc->nnodes--;
 
 	(void)athn_usb_wmi_cmd(usc, AR_WMI_CMD_DISABLE_INTR);
 	(void)athn_usb_wmi_cmd(usc, AR_WMI_CMD_DRAIN_TXQ_ALL);
diff --git a/sys/dev/usb/if_athn_usb.h b/sys/dev/usb/if_athn_usb.h
index ccbd0633d9b..78cf8cfe885 100644
--- a/sys/dev/usb/if_athn_usb.h
+++ b/sys/dev/usb/if_athn_usb.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_athn_usb.h,v 1.4 2013/04/15 09:23:01 mglocker Exp $	*/
+/*	$OpenBSD: if_athn_usb.h,v 1.5 2015/03/02 13:47:08 stsp Exp $	*/
 
 /*-
  * Copyright (c) 2011 Damien Bergamini <damien.bergamini@free.fr>
@@ -458,4 +458,7 @@ struct athn_usb_softc {
 	uint8_t				ep_uapsd;
 	uint8_t				ep_mgmt;
 	uint8_t				ep_data[EDCA_NUM_AC];
+
+	/* Firmware cannot handle more than 8 STAs. */
+	uint8_t				nnodes;
 };