Re: [PATCH RESEND] ath10k: Fix potential Rx ring corruption

From: Ben Greear <greearb@candelatech.com>
To: Vasanthakumar Thiagarajan <vthiagar@qti.qualcomm.com>
Cc: linux-wireless@vger.kernel.org, ath10k@lists.infradead.org
Subject: Re: [PATCH RESEND] ath10k: Fix potential Rx ring corruption
Date: Sat, 10 Jan 2015 11:01:42 -0800	[thread overview]
Message-ID: <54B17716.40609@candelatech.com> (raw)
In-Reply-To: <54B07420.8090600@candelatech.com>

Well, problem is not solved after all.  Had total of 5 crashes on overnight run, must have
all been before midnight, because that is the earliest logs I see (journald was not configured
to use enough space...fixed for next time) and no crashes since then.

Still, it is at least no worse.

I wonder if similar wb() is needed in the firmware somewhere?

Thanks,
Ben

On 01/09/2015 04:36 PM, Ben Greear wrote:
> I added this to my tree (and a bunch more debug stuff to track
> CE transport-ids), and I've done about 4500 station reconnects over
> the last 2 hours and no tx-credits hang issue so far.
>
> Could be my debugging code or that I'm getting lucky, but I'm hopeful
> that your patch actually fixed the problem I was seeing!
>
> Thanks,
> Ben
>
>
> On 01/09/2015 09:19 AM, Vasanthakumar Thiagarajan wrote:
>> When replenishing Rx buffers driver updates the address of the
>> buffer and the index of rx buffer in rx ring to the firmware.
>> Change in order by CPU can cause rx ring corruption. Add memory
>> barrier before updating rx buffer index to guarantee the order.
>>
>> This could fix some instances of rx ring corruption due to done
>> bit in rx attention flag not set.
>>
>> Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@qti.qualcomm.com>
>> ---
>>   drivers/net/wireless/ath/ath10k/htt_rx.c |    5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/net/wireless/ath/ath10k/htt_rx.c b/drivers/net/wireless/ath/ath10k/htt_rx.c
>> index 9c782a4..baa1c44 100644
>> --- a/drivers/net/wireless/ath/ath10k/htt_rx.c
>> +++ b/drivers/net/wireless/ath/ath10k/htt_rx.c
>> @@ -97,6 +97,11 @@ static int __ath10k_htt_rx_ring_fill_n(struct ath10k_htt *htt, int num)
>>   	}
>>
>>   fail:
>> +	/*
>> +	 * Make sure the rx buffer is updated before available buffer
>> +	 * index to avoid any potential rx ring corruption.
>> +	 */
>> +	mb();
>>   	*htt->rx_ring.alloc_idx.vaddr = __cpu_to_le32(idx);
>>   	return ret;
>>   }
>>
>
>

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

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