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ath9k: fix race with IEEE80211_CONF_PS checks

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There is a small window where the mac80211 changes the IEEE80211_CONF_PS
flag, and then informs the driver about the change. We have a race
condition if we are checking the flag in the same time. Avoid it by
introducing a local variable, and using that instead of checking the
IEEE80211_CONF_PS flag directly.

This fix the problem reported by Luis:
http://article.gmane.org/gmane.linux.kernel.wireless.general/34363

Changes-licensed-under: ISC
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Gabor Juhos 2009-07-24 17:27:21 +02:00 committed by John W. Linville
parent ff8365ca88
commit 96148326c4
4 changed files with 12 additions and 15 deletions
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1
drivers/net/wireless/ath/ath9k/ath9k.h
View file

@ -573,6 +573,7 @@ struct ath_softc {
u32 keymax;
DECLARE_BITMAP(keymap, ATH_KEYMAX);
u8 splitmic;
bool ps_enabled;
unsigned long ps_usecount;
enum ath9k_int imask;
enum ath9k_ht_extprotspacing ht_extprotspacing;

17
drivers/net/wireless/ath/ath9k/hw.c
View file

@ -2863,10 +2863,8 @@ void ath9k_ps_wakeup(struct ath_softc *sc)
if (++sc->ps_usecount != 1)
goto unlock;
if (sc->sc_ah->power_mode != ATH9K_PM_AWAKE) {
sc->sc_ah->restore_mode = sc->sc_ah->power_mode;
if (sc->sc_ah->power_mode != ATH9K_PM_AWAKE)
ath9k_hw_setpower_nolock(sc->sc_ah, ATH9K_PM_AWAKE);
}
unlock:
spin_unlock_irqrestore(&sc->sc_pm_lock, flags);
@ -2880,13 +2878,12 @@ void ath9k_ps_restore(struct ath_softc *sc)
if (--sc->ps_usecount != 0)
goto unlock;
if ((sc->hw->conf.flags & IEEE80211_CONF_PS) &&
!(sc->sc_flags & (SC_OP_WAIT_FOR_BEACON |
SC_OP_WAIT_FOR_CAB |
SC_OP_WAIT_FOR_PSPOLL_DATA |
SC_OP_WAIT_FOR_TX_ACK)))
ath9k_hw_setpower_nolock(sc->sc_ah,
sc->sc_ah->restore_mode);
if (sc->ps_enabled &&
!(sc->sc_flags & (SC_OP_WAIT_FOR_BEACON |
SC_OP_WAIT_FOR_CAB |
SC_OP_WAIT_FOR_PSPOLL_DATA |
SC_OP_WAIT_FOR_TX_ACK)))
ath9k_hw_setpower_nolock(sc->sc_ah, ATH9K_PM_NETWORK_SLEEP);
unlock:
spin_unlock_irqrestore(&sc->sc_pm_lock, flags);

1
drivers/net/wireless/ath/ath9k/hw.h
View file

@ -421,7 +421,6 @@ struct ath_hw {
enum nl80211_iftype opmode;
enum ath9k_power_mode power_mode;
enum ath9k_power_mode restore_mode;
struct ath9k_nfcal_hist nfCalHist[NUM_NF_READINGS];
struct ar5416Stats stats;

8
drivers/net/wireless/ath/ath9k/main.c
View file

@ -499,8 +499,7 @@ static void ath9k_tasklet(unsigned long data)
if (status & ATH9K_INT_TX)
ath_tx_tasklet(sc);
if ((status & ATH9K_INT_TSFOOR) &&
(sc->hw->conf.flags & IEEE80211_CONF_PS)) {
if ((status & ATH9K_INT_TSFOOR) && sc->ps_enabled) {
/*
* TSF sync does not look correct; remain awake to sync with
* the next Beacon.
@ -2001,7 +2000,7 @@ static int ath9k_tx(struct ieee80211_hw *hw,
goto exit;
}
if (sc->hw->conf.flags & IEEE80211_CONF_PS) {
if (sc->ps_enabled) {
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
/*
* mac80211 does not set PM field for normal data frames, so we
@ -2289,8 +2288,9 @@ static int ath9k_config(struct ieee80211_hw *hw, u32 changed)
}
ath9k_hw_setrxabort(sc->sc_ah, 1);
}
ath9k_hw_setpower(sc->sc_ah, ATH9K_PM_NETWORK_SLEEP);
sc->ps_enabled = true;
} else {
sc->ps_enabled = false;
ath9k_hw_setpower(sc->sc_ah, ATH9K_PM_AWAKE);
if (!(ah->caps.hw_caps &
ATH9K_HW_CAP_AUTOSLEEP)) {