linux-kernel - Re: [PATCH] dmaengine: pl330: use lock of dma channel in pl330

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Date:   Fri, 9 Sep 2016 20:54:47 +0800
From:   Hsin-yu Chao <hychao@...omium.org>
To:     Vinod Koul <vinod.koul@...el.com>
Cc:     Dan Williams <dan.j.williams@...el.com>,
        "open list:DMA GENERIC OFFLOAD ENGINE SUBSYSTEM" 
        <dmaengine@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] dmaengine: pl330: use lock of dma channel in pl330_update

It turns out this patch could cause lock dependency issue.
The other patch "Acquire dmac's spinlock in pl330_tx_status" that I've
uploaded is the correct fix to replace this one.

Thanks,
Hsin-yu

On Fri, Sep 9, 2016 at 7:48 PM, Vinod Koul <vinod.koul@...el.com> wrote:
> On Fri, Aug 19, 2016 at 09:03:48PM +0800, Hsin-Yu Chao wrote:
>> The content of pl330_thread could be modified in pl330_update
>> without protection by the lock from the dma channel who currently
>> holding this thread. This could cause bug to the calculation of
>> in pl330_tx_status, if the running request has just been done and
>> moving to next request while calculating the residual number, an
>> invalid number from BUSY descriptor could be added up.
>> ---
>>  drivers/dma/pl330.c | 19 +++++++++++++++++++
>>  1 file changed, 19 insertions(+)
>>
>> diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
>> index 31e9c49..2449cb7 100644
>> --- a/drivers/dma/pl330.c
>> +++ b/drivers/dma/pl330.c
>> @@ -1564,6 +1564,19 @@ static void pl330_dotask(unsigned long data)
>>       return;
>>  }
>>
>> +static struct dma_pl330_chan *get_dma_channel(struct pl330_dmac *pl330,
>> +                                           struct pl330_thread *thrd)
>> +{
>> +     struct dma_pl330_chan *pch;
>> +     int i;
>
> empty line here please
>
> --
> ~Vinod