Hi all,
The beacon processing in ath9k is done in a tasklet. This tasklet may race
against beacon allocation/deallocation in process context. The patch below
is an attempt to point out / avoid these race conditions. My hope is that
this will stabilize ath9k in a use-case I'm interested in where ap vif
interfaces are added and removed quite often.
This is purely an RFC, and it's probably synchronizing a bit too much. I'm
currently testing this patch with no obvious problems so far (except for
the part in xmit.c which I've commented out). More testing is necessary
but so is a rewrite of the patch anyway.
Any thoughts?
Best regards,
Björn
---
diff --git a/drivers/net/wireless/ath/ath9k/beacon.c b/drivers/net/wireless/ath/ath9k/beacon.c
index 19891e7..f91e0b5 100644
--- a/drivers/net/wireless/ath/ath9k/beacon.c
+++ b/drivers/net/wireless/ath/ath9k/beacon.c
@@ -192,6 +192,7 @@ static struct ath_buf *ath_beacon_generate(struct ieee80211_hw *hw,
if (sc->nvifs > 1) {
ath_print(common, ATH_DBG_BEACON,
"Flushing previous cabq traffic\n");
+ ath9k_hw_stoptxdma(sc->sc_ah, cabq->axq_qnum);
ath_draintxq(sc, cabq, false);
}
}
diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index b52f1cf..c3d2a36 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -290,9 +290,11 @@ int ath_set_channel(struct ath_softc *sc, struct ieee80211_hw *hw,
ath9k_hw_set_interrupts(ah, ah->imask);
if (!(sc->sc_flags & (SC_OP_OFFCHANNEL))) {
+ tasklet_disable(&sc->bcon_tasklet);
ath_beacon_config(sc, NULL);
ieee80211_queue_delayed_work(sc->hw, &sc->tx_complete_work, 0);
ath_start_ani(common);
+ tasklet_enable(&sc->bcon_tasklet);
}
ps_restore:
@@ -838,6 +840,8 @@ static void ath9k_bss_assoc_info(struct ath_softc *sc,
struct ath_common *common = ath9k_hw_common(ah);
if (bss_conf->assoc) {
+ tasklet_disable(&sc->bcon_tasklet);
+
ath_print(common, ATH_DBG_CONFIG,
"Bss Info ASSOC %d, bssid: %pM\n",
bss_conf->aid, common->curbssid);
@@ -861,6 +865,8 @@ static void ath9k_bss_assoc_info(struct ath_softc *sc,
sc->sc_flags |= SC_OP_ANI_RUN;
ath_start_ani(common);
+
+ tasklet_enable(&sc->bcon_tasklet);
} else {
ath_print(common, ATH_DBG_CONFIG, "Bss Info DISASSOC\n");
common->curaid = 0;
@@ -903,8 +909,11 @@ void ath_radio_enable(struct ath_softc *sc, struct ieee80211_hw *hw)
}
spin_unlock_bh(&sc->rx.pcu_lock);
- if (sc->sc_flags & SC_OP_BEACONS)
+ if (sc->sc_flags & SC_OP_BEACONS) {
+ tasklet_disable(&sc->bcon_tasklet);
ath_beacon_config(sc, NULL); /* restart beacons */
+ tasklet_enable(&sc->bcon_tasklet);
+ }
/* Re-Enable interrupts */
ath9k_hw_set_interrupts(ah, ah->imask);
@@ -1008,8 +1017,11 @@ int ath_reset(struct ath_softc *sc, bool retry_tx)
*/
ath_update_txpow(sc);
- if ((sc->sc_flags & SC_OP_BEACONS) || !(sc->sc_flags & (SC_OP_OFFCHANNEL)))
+ if ((sc->sc_flags & SC_OP_BEACONS) || !(sc->sc_flags & (SC_OP_OFFCHANNEL))) {
+ tasklet_disable(&sc->bcon_tasklet);
ath_beacon_config(sc, NULL); /* restart beacons */
+ tasklet_enable(&sc->bcon_tasklet);
+ }
ath9k_hw_set_interrupts(ah, ah->imask);
@@ -1517,6 +1529,8 @@ static void ath9k_remove_interface(struct ieee80211_hw *hw,
mutex_lock(&sc->mutex);
+ tasklet_disable(&sc->bcon_tasklet);
+
/* Stop ANI */
sc->sc_flags &= ~SC_OP_ANI_RUN;
del_timer_sync(&common->ani.timer);
@@ -1544,6 +1558,8 @@ static void ath9k_remove_interface(struct ieee80211_hw *hw,
sc->nvifs--;
+ tasklet_enable(&sc->bcon_tasklet);
+
mutex_unlock(&sc->mutex);
}
@@ -1817,6 +1833,8 @@ static int ath9k_conf_tx(struct ieee80211_hw *hw, u16 queue,
mutex_lock(&sc->mutex);
+ tasklet_disable(&sc->bcon_tasklet);
+
memset(&qi, 0, sizeof(struct ath9k_tx_queue_info));
qi.tqi_aifs = params->aifs;
@@ -1839,6 +1857,8 @@ static int ath9k_conf_tx(struct ieee80211_hw *hw, u16 queue,
if ((qnum == sc->tx.hwq_map[WME_AC_BE]) && !ret)
ath_beaconq_config(sc);
+ tasklet_enable(&sc->bcon_tasklet);
+
mutex_unlock(&sc->mutex);
return ret;
@@ -1930,13 +1950,16 @@ static void ath9k_bss_info_changed(struct ieee80211_hw *hw,
/* Enable transmission of beacons (AP, IBSS, MESH) */
if ((changed & BSS_CHANGED_BEACON) ||
((changed & BSS_CHANGED_BEACON_ENABLED) && bss_conf->enable_beacon)) {
+ tasklet_disable(&sc->bcon_tasklet);
ath9k_hw_stoptxdma(sc->sc_ah, sc->beacon.beaconq);
error = ath_beacon_alloc(aphy, vif);
if (!error)
ath_beacon_config(sc, vif);
+ tasklet_enable(&sc->bcon_tasklet);
}
if (changed & BSS_CHANGED_ERP_SLOT) {
+ tasklet_disable(&sc->bcon_tasklet);
if (bss_conf->use_short_slot)
slottime = 9;
else
@@ -1953,6 +1976,7 @@ static void ath9k_bss_info_changed(struct ieee80211_hw *hw,
ah->slottime = slottime;
ath9k_hw_init_global_settings(ah);
}
+ tasklet_enable(&sc->bcon_tasklet);
}
/* Disable transmission of beacons */
@@ -1960,6 +1984,7 @@ static void ath9k_bss_info_changed(struct ieee80211_hw *hw,
ath9k_hw_stoptxdma(sc->sc_ah, sc->beacon.beaconq);
if (changed & BSS_CHANGED_BEACON_INT) {
+ tasklet_disable(&sc->bcon_tasklet);
sc->beacon_interval = bss_conf->beacon_int;
/*
* In case of AP mode, the HW TSF has to be reset
@@ -1974,6 +1999,7 @@ static void ath9k_bss_info_changed(struct ieee80211_hw *hw,
} else {
ath_beacon_config(sc, vif);
}
+ tasklet_enable(&sc->bcon_tasklet);
}
if (changed & BSS_CHANGED_ERP_PREAMBLE) {
diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index f2ade24..174a8ae 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -1133,6 +1133,10 @@ void ath_drain_all_txq(struct ath_softc *sc, bool retry_tx)
/* Stop beacon queue */
ath9k_hw_stoptxdma(sc->sc_ah, sc->beacon.beaconq);
+ /* Stop cab queue */
+ if (sc->beacon.cabq != NULL)
+ ath9k_hw_stoptxdma(sc->sc_ah, sc->beacon.cabq->axq_qnum);
+
/* Stop data queues */
for (i = 0; i < ATH9K_NUM_TX_QUEUES; i++) {
if (ATH_TXQ_SETUP(sc, i)) {
@@ -1157,6 +1161,11 @@ void ath_drain_all_txq(struct ath_softc *sc, bool retry_tx)
spin_unlock_bh(&sc->sc_resetlock);
}
+ /* Drain cab queue
+ * BUG: for some reason this causes a dump in ath_draintxq(). Why?
+ if (sc->beacon.cabq != NULL)
+ ath_draintxq(sc->sc_ah, sc->beacon.cabq, false); */
+
for (i = 0; i < ATH9K_NUM_TX_QUEUES; i++) {
if (ATH_TXQ_SETUP(sc, i))
ath_draintxq(sc, &sc->tx.txq[i], retry_tx);
