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ath9k: fix a DMA related race condition on reset

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When ath_drain_all_txq fails to stop DMA, it issues a hw reset. This reset
happens at a very problematic point in time, when the hardware rx path has
not been stopped yet. This could lead to memory corruption, hardware hangs
or other issues.
To fix these issues, simply remove the reset entirely and check the tx DMA
stop status to prevent problems with fast channel changes.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Felix Fietkau
2010-12-05 20:17:53 +01:00
committed by John W. Linville
parent 841051602e
commit 080e1a259a
3 changed files with 10 additions and 19 deletions
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22
drivers/net/wireless/ath/ath9k/xmit.c
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@@ -1120,7 +1120,7 @@ void ath_draintxq(struct ath_softc *sc, struct ath_txq *txq, bool retry_tx)
}
}
void ath_drain_all_txq(struct ath_softc *sc, bool retry_tx)
bool ath_drain_all_txq(struct ath_softc *sc, bool retry_tx)
{
struct ath_hw *ah = sc->sc_ah;
struct ath_common *common = ath9k_hw_common(sc->sc_ah);
@@ -1128,7 +1128,7 @@ void ath_drain_all_txq(struct ath_softc *sc, bool retry_tx)
int i, npend = 0;
if (sc->sc_flags & SC_OP_INVALID)
return;
return true;
/* Stop beacon queue */
ath9k_hw_stoptxdma(sc->sc_ah, sc->beacon.beaconq);
@@ -1142,25 +1142,15 @@ void ath_drain_all_txq(struct ath_softc *sc, bool retry_tx)
}
}
if (npend) {
int r;
ath_print(common, ATH_DBG_FATAL,
"Failed to stop TX DMA. Resetting hardware!\n");
spin_lock_bh(&sc->sc_resetlock);
r = ath9k_hw_reset(ah, sc->sc_ah->curchan, ah->caldata, false);
if (r)
ath_print(common, ATH_DBG_FATAL,
"Unable to reset hardware; reset status %d\n",
r);
spin_unlock_bh(&sc->sc_resetlock);
}
if (npend)
ath_print(common, ATH_DBG_FATAL, "Failed to stop TX DMA!\n");
for (i = 0; i < ATH9K_NUM_TX_QUEUES; i++) {
if (ATH_TXQ_SETUP(sc, i))
ath_draintxq(sc, &sc->tx.txq[i], retry_tx);
}
return !npend;
}
void ath_tx_cleanupq(struct ath_softc *sc, struct ath_txq *txq)