Simplify iwm(4) newstate task by only queuing one state transition

at a time. The newstate task now always transitions to the most
recently requested state, rather than hopping along with every request.

This allows us get rid of the silly newstate generation counter, and
we can now task_del() a pending transition when the interface goes down.
While several issues with this driver remain, I believe this change
does not introduce new problems.

Tested by myself, jasper@, and zhuk@

2 files changed, 26 insertions, 53 deletions

diff --git a/sys/dev/pci/if_iwm.c b/sys/dev/pci/if_iwm.c
index 3d9eee6fbbd..6e80b574b9d 100644
--- a/sys/dev/pci/if_iwm.c
+++ b/sys/dev/pci/if_iwm.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_iwm.c,v 1.51 2015/09/27 16:53:38 stsp Exp $	*/
+/*	$OpenBSD: if_iwm.c,v 1.52 2015/10/05 13:05:08 stsp Exp $	*/
 
 /*
  * Copyright (c) 2014 genua mbh <info@genua.de>
@@ -195,14 +195,6 @@ const struct iwm_rate {
 #define IWM_RIDX_IS_CCK(_i_) ((_i_) < IWM_RIDX_OFDM)
 #define IWM_RIDX_IS_OFDM(_i_) ((_i_) >= IWM_RIDX_OFDM)
 
-struct iwm_newstate_state {
-	struct task ns_wk;
-	struct ieee80211com *ns_ic;
-	enum ieee80211_state ns_nstate;
-	int ns_arg;
-	int ns_generation;
-};
-
 int	iwm_store_cscheme(struct iwm_softc *, uint8_t *, size_t);
 int	iwm_firmware_store_section(struct iwm_softc *, enum iwm_ucode_type,
 					uint8_t *, size_t);
@@ -406,7 +398,7 @@ struct ieee80211_node *iwm_node_alloc(struct ieee80211com *);
 void	iwm_calib_timeout(void *);
 void	iwm_setrates(struct iwm_node *);
 int	iwm_media_change(struct ifnet *);
-void	iwm_newstate_cb(void *);
+void	iwm_newstate_task(void *);
 int	iwm_newstate(struct ieee80211com *, enum ieee80211_state, int);
 void	iwm_endscan_cb(void *);
 int	iwm_init_hw(struct iwm_softc *);
@@ -5263,43 +5255,29 @@ iwm_media_change(struct ifnet *ifp)
 }
 
 void
-iwm_newstate_cb(void *wk)
+iwm_newstate_task(void *psc)
 {
-	struct iwm_newstate_state *iwmns = (void *)wk;
-	struct ieee80211com *ic = iwmns->ns_ic;
-	enum ieee80211_state nstate = iwmns->ns_nstate;
-	int generation = iwmns->ns_generation;
+	struct iwm_softc *sc = (struct iwm_softc *)psc;
+	struct ieee80211com *ic = &sc->sc_ic;
+	enum ieee80211_state nstate = sc->ns_nstate;
+	enum ieee80211_state ostate = ic->ic_state;
 	struct iwm_node *in;
-	int arg = iwmns->ns_arg;
-	struct ifnet *ifp = IC2IFP(ic);
-	struct iwm_softc *sc = ifp->if_softc;
+	int arg = sc->ns_arg;
 	int error;
 
-	free(iwmns, M_DEVBUF, sizeof(*iwmns));
-
-	DPRINTF(("Prepare to switch state %s->%s\n",
-	    ieee80211_state_name[ic->ic_state],
-	    ieee80211_state_name[nstate]));
-	if (sc->sc_generation != generation) {
-		DPRINTF(("newstate_cb: someone pulled the plug meanwhile\n"));
-		if (nstate == IEEE80211_S_INIT) {
-			DPRINTF(("newstate_cb: nstate == IEEE80211_S_INIT: calling sc_newstate()\n"));
-			sc->sc_newstate(ic, nstate, arg);
-		}
-		return;
-	}
-
 	DPRINTF(("switching state %s->%s\n",
-	    ieee80211_state_name[ic->ic_state],
+	    ieee80211_state_name[ostate],
 	    ieee80211_state_name[nstate]));
 
-	if (ic->ic_state == IEEE80211_S_SCAN && nstate != ic->ic_state)
+	if (ostate == IEEE80211_S_SCAN && nstate != ostate)
 		iwm_led_blink_stop(sc);
 
 	/* disable beacon filtering if we're hopping out of RUN */
-	if (ic->ic_state == IEEE80211_S_RUN && nstate != ic->ic_state) {
+	if (ostate == IEEE80211_S_RUN && nstate != ostate)
 		iwm_mvm_disable_beacon_filter(sc, (void *)ic->ic_bss);
 
+	/* Reset the device if moving out of AUTH, ASSOC, or RUN. */
+	if (ostate > IEEE80211_S_SCAN && nstate < ostate) {
 		if (((in = (void *)ic->ic_bss) != NULL))
 			in->in_assoc = 0;
 		iwm_release(sc, NULL);
@@ -5393,25 +5371,15 @@ iwm_newstate_cb(void *wk)
 int
 iwm_newstate(struct ieee80211com *ic, enum ieee80211_state nstate, int arg)
 {
-	struct iwm_newstate_state *iwmns;
 	struct ifnet *ifp = IC2IFP(ic);
 	struct iwm_softc *sc = ifp->if_softc;
 
 	timeout_del(&sc->sc_calib_to);
 
-	iwmns = malloc(sizeof(*iwmns), M_DEVBUF, M_NOWAIT);
-	if (!iwmns) {
-		DPRINTF(("%s: allocating state cb mem failed\n", DEVNAME(sc)));
-		return ENOMEM;
-	}
-
-	iwmns->ns_ic = ic;
-	iwmns->ns_nstate = nstate;
-	iwmns->ns_arg = arg;
-	iwmns->ns_generation = sc->sc_generation;
+	sc->ns_nstate = nstate;
+	sc->ns_arg = arg;
 
-	task_set(&iwmns->ns_wk, iwm_newstate_cb, iwmns);
-	task_add(sc->sc_nswq, &iwmns->ns_wk);
+	task_add(sc->sc_nswq, &sc->newstate_task);
 
 	return 0;
 }
@@ -5676,8 +5644,10 @@ iwm_stop(struct ifnet *ifp, int disable)
 	ic->ic_scan_lock = IEEE80211_SCAN_UNLOCKED;
 	ifp->if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);
 
-	if (ic->ic_state != IEEE80211_S_INIT)
-		ieee80211_new_state(ic, IEEE80211_S_INIT, -1);
+	task_del(systq, &sc->init_task);
+	task_del(sc->sc_nswq, &sc->newstate_task);
+	task_del(sc->sc_eswq, &sc->sc_eswk);
+	sc->sc_newstate(ic, IEEE80211_S_INIT, -1);
 
 	timeout_del(&sc->sc_calib_to);
 	iwm_led_blink_stop(sc);
@@ -6614,6 +6584,7 @@ iwm_attach(struct device *parent, struct device *self, void *aux)
 	timeout_set(&sc->sc_calib_to, iwm_calib_timeout, sc);
 	timeout_set(&sc->sc_led_blink_to, iwm_led_blink_timeout, sc);
 	task_set(&sc->init_task, iwm_init_task, sc);
+	task_set(&sc->newstate_task, iwm_newstate_task, sc);
 
 	/*
 	 * We cannot read the MAC address without loading the
@@ -6687,8 +6658,7 @@ iwm_wakeup(struct iwm_softc *sc)
 	reg = pci_conf_read(sc->sc_pct, sc->sc_pcitag, 0x40);
 	pci_conf_write(sc->sc_pct, sc->sc_pcitag, 0x40, reg & ~0xff00);
 
-	iwm_init_task(sc);
-
+	task_add(systq, &sc->init_task);
 }
 
 int
diff --git a/sys/dev/pci/if_iwmvar.h b/sys/dev/pci/if_iwmvar.h
index 96f5eec5044..7644ec8f306 100644
--- a/sys/dev/pci/if_iwmvar.h
+++ b/sys/dev/pci/if_iwmvar.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_iwmvar.h,v 1.9 2015/06/15 08:06:12 stsp Exp $	*/
+/*	$OpenBSD: if_iwmvar.h,v 1.10 2015/10/05 13:05:08 stsp Exp $	*/
 
 /*
  * Copyright (c) 2014 genua mbh <info@genua.de>
@@ -364,6 +364,9 @@ struct iwm_softc {
 	struct timeout sc_led_blink_to;
 
 	struct task		init_task;
+	struct task		newstate_task;
+	enum ieee80211_state	ns_nstate;
+	int			ns_arg;
 
 	bus_space_tag_t sc_st;
 	bus_space_handle_t sc_sh;