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Date:      Fri, 10 May 2013 10:10:01 GMT
From:      dfilter@FreeBSD.ORG (dfilter service)
To:        freebsd-bugs@FreeBSD.org
Subject:   Re: kern/178477: commit references a PR
Message-ID:  <201305101010.r4AAA1wh091430@freefall.freebsd.org>
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The following reply was made to PR kern/178477; it has been noted by GNATS.

From: dfilter@FreeBSD.ORG (dfilter service)
To: bug-followup@FreeBSD.org
Cc:  
Subject: Re: kern/178477: commit references a PR
Date: Fri, 10 May 2013 10:06:53 +0000 (UTC)

 Author: adrian
 Date: Fri May 10 10:06:45 2013
 New Revision: 250444
 URL: http://svnweb.freebsd.org/changeset/base/250444
 
 Log:
   Make sure the holding descriptor and link pointer are both freed during
   a non-loss reset.
   
   When the drain functions are called, the holding descriptor and link pointers
   are NULLed out.
   
   But when the processq function is called during a non-loss reset, this
   doesn't occur.  So the next time a DMA occurs, it's chained to a descriptor
   that no longer exists and the hardware gets angry.
   
   Tested:
   
   * AR5416, STA mode; use sysctl dev.ath.X.forcebstuck=1 to force a non-loss
     reset.
   
   TODO:
   
   * Further AR9380 testing just to check that the behaviour for the EDMA
     chips is sane.
   
   PR:		kern/178477
 
 Modified:
   head/sys/dev/ath/if_ath.c
   head/sys/dev/ath/if_ath_tx_edma.c
 
 Modified: head/sys/dev/ath/if_ath.c
 ==============================================================================
 --- head/sys/dev/ath/if_ath.c	Fri May 10 09:58:32 2013	(r250443)
 +++ head/sys/dev/ath/if_ath.c	Fri May 10 10:06:45 2013	(r250444)
 @@ -4668,9 +4668,21 @@ ath_legacy_tx_drain(struct ath_softc *sc
  			if (sc->sc_debug & ATH_DEBUG_RESET)
  				ath_tx_dump(sc, &sc->sc_txq[i]);
  #endif	/* ATH_DEBUG */
 -			if (reset_type == ATH_RESET_NOLOSS)
 +			if (reset_type == ATH_RESET_NOLOSS) {
  				ath_tx_processq(sc, &sc->sc_txq[i], 0);
 -			else
 +				ATH_TXQ_LOCK(&sc->sc_txq[i]);
 +				/*
 +				 * Free the holding buffer; DMA is now
 +				 * stopped.
 +				 */
 +				ath_txq_freeholdingbuf(sc, &sc->sc_txq[i]);
 +				/*
 +				 * Reset the link pointer to NULL; there's
 +				 * no frames to chain DMA to.
 +				 */
 +				sc->sc_txq[i].axq_link = NULL;
 +				ATH_TXQ_UNLOCK(&sc->sc_txq[i]);
 +			} else
  				ath_tx_draintxq(sc, &sc->sc_txq[i]);
  		}
  	}
 
 Modified: head/sys/dev/ath/if_ath_tx_edma.c
 ==============================================================================
 --- head/sys/dev/ath/if_ath_tx_edma.c	Fri May 10 09:58:32 2013	(r250443)
 +++ head/sys/dev/ath/if_ath_tx_edma.c	Fri May 10 10:06:45 2013	(r250444)
 @@ -551,6 +551,22 @@ ath_edma_tx_drain(struct ath_softc *sc, 
  	 */
  	if (reset_type == ATH_RESET_NOLOSS) {
  		ath_edma_tx_processq(sc, 0);
 +		for (i = 0; i < HAL_NUM_TX_QUEUES; i++) {
 +			if (ATH_TXQ_SETUP(sc, i)) {
 +				ATH_TXQ_LOCK(&sc->sc_txq[i]);
 +				/*
 +				 * Free the holding buffer; DMA is now
 +				 * stopped.
 +				 */
 +				ath_txq_freeholdingbuf(sc, &sc->sc_txq[i]);
 +				/*
 +				 * Reset the link pointer to NULL; there's
 +				 * no frames to chain DMA to.
 +				 */
 +				sc->sc_txq[i].axq_link = NULL;
 +				ATH_TXQ_UNLOCK(&sc->sc_txq[i]);
 +			}
 +		}
  	} else {
  		for (i = 0; i < HAL_NUM_TX_QUEUES; i++) {
  			if (ATH_TXQ_SETUP(sc, i))
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