linux-kernel - Re: [PATCH 6/6] dmaengine: tegra-apb: Disable interrupts on removal

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Date:	Fri, 16 Oct 2015 12:40:42 +0200
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Jon Hunter <jonathanh@...dia.com>,
	Laxman Dewangan <ldewangan@...dia.com>,
	Vinod Koul <vinod.koul@...el.com>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Alexandre Courbot <gnurou@...il.com>
CC:	dmaengine@...r.kernel.org, linux-tegra@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/6] dmaengine: tegra-apb: Disable interrupts on removal

On 10/16/2015 11:29 AM, Jon Hunter wrote:
> 
> On 16/10/15 09:53, Lars-Peter Clausen wrote:
>> On 10/16/2015 10:25 AM, Jon Hunter wrote:
>>> On driver removal, before killing any tasklets, ensure that the channel
>>> interrupts are disabled so that the tasklet will not try to run during
>>> or after the removal of the driver.
>>>
>>> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
>>> ---
>>>  drivers/dma/tegra20-apb-dma.c | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
>>> index 2bfab8d28b53..0dd6e7deaa8e 100644
>>> --- a/drivers/dma/tegra20-apb-dma.c
>>> +++ b/drivers/dma/tegra20-apb-dma.c
>>> @@ -1492,6 +1492,7 @@ static int tegra_dma_remove(struct platform_device *pdev)
>>>  
>>>  	for (i = 0; i < tdma->chip_data->nr_channels; ++i) {
>>>  		tdc = &tdma->channels[i];
>>> +		disable_irq(tdc->irq);
>>
>> How about just calling free_irq()? That's how you'd typically handle this.
> 
> Yes, however, the interrupt is requested by devm_request_irq(). I guess
> I could call devm_free_irq() here?

Just use request_irq() instead of devm_request_irq(). You have the same
issue on the error path in the probe function anyway and also need to add
the free_irq() before the tasklet_kill() there as well.

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