kern/179232: commit references a PR

[dfilter service]

The following reply was made to PR kern/179232; it has been noted by GNATS.

From: dfilter at FreeBSD.ORG (dfilter service)
To: bug-followup at FreeBSD.org
Cc:  
Subject: Re: kern/179232: commit references a PR
Date: Mon,  3 Jun 2013 19:39:50 +0000 (UTC)

 Author: adrian
 Date: Mon Jun  3 19:39:37 2013
 New Revision: 251342
 URL: http://svnweb.freebsd.org/changeset/base/251342
 
 Log:
   Fix the order of TX shutdown and reset.
   
   * Grab the reset lock first, so any subsequent interrupt, TX, RX work
     will fail
   
   * Then shut down interrupts
   
   * Then wait for TX/RX to finish running
   
   At this point no further work will be running, so it's safe to do the
   reset path code.
   
   PR:		kern/179232
 
 Modified:
   head/sys/dev/ath/if_ath.c
 
 Modified: head/sys/dev/ath/if_ath.c
 ==============================================================================
 --- head/sys/dev/ath/if_ath.c	Mon Jun  3 19:29:03 2013	(r251341)
 +++ head/sys/dev/ath/if_ath.c	Mon Jun  3 19:39:37 2013	(r251342)
 @@ -2328,12 +2328,27 @@ ath_reset(struct ifnet *ifp, ATH_RESET_T
  	taskqueue_block(sc->sc_tq);
  
  	ATH_PCU_LOCK(sc);
 -	ath_hal_intrset(ah, 0);		/* disable interrupts */
 -	ath_txrx_stop_locked(sc);	/* Ensure TX/RX is stopped */
 +
 +	/*
 +	 * Grab the reset lock before TX/RX is stopped.
 +	 *
 +	 * This is needed to ensure that when the TX/RX actually does finish,
 +	 * no further TX/RX/reset runs in parallel with this.
 +	 */
  	if (ath_reset_grablock(sc, 1) == 0) {
  		device_printf(sc->sc_dev, "%s: concurrent reset! Danger!\n",
  		    __func__);
  	}
 +
 +	/* disable interrupts */
 +	ath_hal_intrset(ah, 0);
 +
 +	/*
 +	 * Now, ensure that any in progress TX/RX completes before we
 +	 * continue.
 +	 */
 +	ath_txrx_stop_locked(sc);
 +
  	ATH_PCU_UNLOCK(sc);
  
  	/*
 @@ -4871,12 +4886,18 @@ ath_chan_set(struct ath_softc *sc, struc
  	taskqueue_block(sc->sc_tq);
  
  	ATH_PCU_LOCK(sc);
 -	ath_hal_intrset(ah, 0);		/* Stop new RX/TX completion */
 -	ath_txrx_stop_locked(sc);	/* Stop pending RX/TX completion */
 +
 +	/* Stop new RX/TX/interrupt completion */
  	if (ath_reset_grablock(sc, 1) == 0) {
  		device_printf(sc->sc_dev, "%s: concurrent reset! Danger!\n",
  		    __func__);
  	}
 +
 +	ath_hal_intrset(ah, 0);
 +
 +	/* Stop pending RX/TX completion */
 +	ath_txrx_stop_locked(sc);
 +
  	ATH_PCU_UNLOCK(sc);
  
  	DPRINTF(sc, ATH_DEBUG_RESET, "%s: %u (%u MHz, flags 0x%x)\n",
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