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From: Kalle Valo <kvalo@qca.qualcomm.com>
To: Michal Kazior <michal.kazior@tieto.com>
Cc: linux-wireless <linux-wireless@vger.kernel.org>,
	Rajkumar Manoharan <rmanohar@qti.qualcomm.com>,
	"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>
Subject: Re: [PATCH] ath10k: fix kernel panic while shutting down AP
Date: Wed, 8 Oct 2014 15:37:00 +0300	[thread overview]
Message-ID: <87fveyg2kz.fsf@kamboji.qca.qualcomm.com> (raw)
In-Reply-To: <CA+BoTQmOZiPQRWeiZ6QqZ5MhHbweMsdf94v1f5mkYpr2461j4A@mail.gmail.com> (Michal Kazior's message of "Wed, 8 Oct 2014 14:24:18 +0200")

Michal Kazior <michal.kazior@tieto.com> writes:

>>> 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.
>
> beacon_buf is protected by conf_mutex implicitly. It wasn't the main
> intent. It is protected with data_lock spinlock.
>
> Do not trust the device - if there's a spurious SWBA event while
> ath10k_remove_interface() is running you could end up with invalid
> memory access.
>
> It might be acceptable to drop the spinlock for ath10k_halt() since
> the device is guaranteed to be stopped at that point (effectively
> reset) though.
>
> Anyway I'm hoping this bug can be fixed with the gfp flag.

Yeah, fixing this with the gfp flag would be much better solution.

-- 
Kalle Valo

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

WARNING: multiple messages have this Message-ID (diff)
From: Kalle Valo <kvalo@qca.qualcomm.com>
To: Michal Kazior <michal.kazior@tieto.com>
Cc: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>
Subject: Re: [PATCH] ath10k: fix kernel panic while shutting down AP
Date: Wed, 8 Oct 2014 15:37:00 +0300	[thread overview]
Message-ID: <87fveyg2kz.fsf@kamboji.qca.qualcomm.com> (raw)
In-Reply-To: <CA+BoTQmOZiPQRWeiZ6QqZ5MhHbweMsdf94v1f5mkYpr2461j4A@mail.gmail.com> (Michal Kazior's message of "Wed, 8 Oct 2014 14:24:18 +0200")

Michal Kazior <michal.kazior@tieto.com> writes:

>>> 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.
>
> beacon_buf is protected by conf_mutex implicitly. It wasn't the main
> intent. It is protected with data_lock spinlock.
>
> Do not trust the device - if there's a spurious SWBA event while
> ath10k_remove_interface() is running you could end up with invalid
> memory access.
>
> It might be acceptable to drop the spinlock for ath10k_halt() since
> the device is guaranteed to be stopped at that point (effectively
> reset) though.
>
> Anyway I'm hoping this bug can be fixed with the gfp flag.

Yeah, fixing this with the gfp flag would be much better solution.

-- 
Kalle Valo

  reply	other threads:[~2014-10-08 12:37 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
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 [this message]
2014-10-08 12:37         ` Kalle Valo

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