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From: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
To: Kalle Valo <kvalo@qca.qualcomm.com>
Cc: linux-wireless@vger.kernel.org,
	Michal Kazior <michal.kazior@tieto.com>,
	ath10k@lists.infradead.org
Subject: Re: [PATCH] ath10k: fix kernel panic while shutting down AP
Date: Wed, 8 Oct 2014 16:18:25 +0530	[thread overview]
Message-ID: <20141008104823.GB25666@qca.qualcomm.com> (raw)
In-Reply-To: <87a956hosb.fsf@kamboji.qca.qualcomm.com>

On Wed, Oct 08, 2014 at 12:52:04PM +0300, Kalle Valo wrote:
> Rajkumar Manoharan <rmanohar@qti.qualcomm.com> writes:
> 
> > The commit "ath10k: workaround fw beaconing bug" is freeing
> > DMA-coherent memory in irq context which is hitting BUG ON
> > in ARM platforms. Fix this by moving dma_free out of spin
> > lock.
 
> [...]
> 
> > @@ -2404,8 +2389,15 @@ void ath10k_halt(struct ath10k *ar)
> >  
> >  	spin_lock_bh(&ar->data_lock);
> >  	list_for_each_entry(arvif, &ar->arvifs, list)
> > -		ath10k_mac_vif_beacon_cleanup(arvif);
> > +		ath10k_mac_vif_beacon_free(arvif);
> >  	spin_unlock_bh(&ar->data_lock);
> > +	list_for_each_entry(arvif, &ar->arvifs, list) {
> > +		if (!arvif->beacon_buf)
> > +			continue;
> > +		dma_free_coherent(ar->dev, IEEE80211_MAX_FRAME_LEN,
> > +				  arvif->beacon_buf, arvif->beacon_paddr);
> > +		arvif->beacon_buf = NULL;
> > +	}
> >  }
> 
> Until now we have protected arvif->beacon_buf with data_lock. How do we
> know that this is safe to do without taking data_lock?
> 
As said, spin_lock can not be used for dma_free_coherent.
arvif->beacon_buf is already protected by conf_mutex. At this state
in ath10k_halt path, no one can access beacon_buf. So mutex lock itself
is sufficient.

-Rajkumar

_______________________________________________
ath10k mailing list
ath10k@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/ath10k

WARNING: multiple messages have this Message-ID (diff)
From: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
To: Kalle Valo <kvalo@qca.qualcomm.com>
Cc: <ath10k@lists.infradead.org>, <linux-wireless@vger.kernel.org>,
	"Michal Kazior" <michal.kazior@tieto.com>
Subject: Re: [PATCH] ath10k: fix kernel panic while shutting down AP
Date: Wed, 8 Oct 2014 16:18:25 +0530	[thread overview]
Message-ID: <20141008104823.GB25666@qca.qualcomm.com> (raw)
In-Reply-To: <87a956hosb.fsf@kamboji.qca.qualcomm.com>

On Wed, Oct 08, 2014 at 12:52:04PM +0300, Kalle Valo wrote:
> Rajkumar Manoharan <rmanohar@qti.qualcomm.com> writes:
> 
> > The commit "ath10k: workaround fw beaconing bug" is freeing
> > DMA-coherent memory in irq context which is hitting BUG ON
> > in ARM platforms. Fix this by moving dma_free out of spin
> > lock.
 
> [...]
> 
> > @@ -2404,8 +2389,15 @@ void ath10k_halt(struct ath10k *ar)
> >  
> >  	spin_lock_bh(&ar->data_lock);
> >  	list_for_each_entry(arvif, &ar->arvifs, list)
> > -		ath10k_mac_vif_beacon_cleanup(arvif);
> > +		ath10k_mac_vif_beacon_free(arvif);
> >  	spin_unlock_bh(&ar->data_lock);
> > +	list_for_each_entry(arvif, &ar->arvifs, list) {
> > +		if (!arvif->beacon_buf)
> > +			continue;
> > +		dma_free_coherent(ar->dev, IEEE80211_MAX_FRAME_LEN,
> > +				  arvif->beacon_buf, arvif->beacon_paddr);
> > +		arvif->beacon_buf = NULL;
> > +	}
> >  }
> 
> Until now we have protected arvif->beacon_buf with data_lock. How do we
> know that this is safe to do without taking data_lock?
> 
As said, spin_lock can not be used for dma_free_coherent.
arvif->beacon_buf is already protected by conf_mutex. At this state
in ath10k_halt path, no one can access beacon_buf. So mutex lock itself
is sufficient.

-Rajkumar

  reply	other threads:[~2014-10-08 10:47 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-08  9:16 [PATCH] ath10k: fix kernel panic while shutting down AP Rajkumar Manoharan
2014-10-08  9:16 ` Rajkumar Manoharan
2014-10-08  9:45 ` Michal Kazior
2014-10-08  9:45   ` Michal Kazior
2014-10-08 10:33   ` Rajkumar Manoharan
2014-10-08 10:33     ` Rajkumar Manoharan
2014-10-08 10:50     ` Michal Kazior
2014-10-08 10:50       ` Michal Kazior
2014-10-08 11:08       ` Rajkumar Manoharan
2014-10-08 11:08         ` Rajkumar Manoharan
2014-10-08 11:13         ` Rajkumar Manoharan
2014-10-08 11:13           ` Rajkumar Manoharan
2014-10-08 12:17           ` Michal Kazior
2014-10-08 12:17             ` Michal Kazior
2014-10-08 12:16         ` Michal Kazior
2014-10-08 12:16           ` Michal Kazior
2014-10-10  9:36           ` Rajkumar Manoharan
2014-10-10  9:36             ` Rajkumar Manoharan
2014-10-08  9:52 ` Kalle Valo
2014-10-08  9:52   ` Kalle Valo
2014-10-08 10:48   ` Rajkumar Manoharan [this message]
2014-10-08 10:48     ` Rajkumar Manoharan
2014-10-08 12:24     ` Michal Kazior
2014-10-08 12:24       ` Michal Kazior
2014-10-08 12:37       ` Kalle Valo
2014-10-08 12:37         ` Kalle Valo

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