Re: [PATCH 1/2] dmaengine: TXx9 Soc DMA Controller driver

From: Dan Williams
Date: Tue Mar 17 2009 - 13:02:25 EST


On Tue, Mar 17, 2009 at 9:09 AM, Atsushi Nemoto <anemo@xxxxxxxxxxxxx> wrote:
> On Mon, 16 Mar 2009 21:52:10 -0700, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
>> > Hmm.. why idr_ref is dynamically allocated?  Just putting it in
>> > dma_device makes thing more simple, no?
>>
>> The sysfs device has a longer lifetime than dma_device.  See commit
>> 41d5e59c [1].
>
> The sysfs device for dma_chan (dma_chan_dev) has a shorter lifetime
> than dma_device, doesn't it?

No, dma_async_device_unregister(), and the freeing of dma_device, may
finish before chan_dev_release is called. Userspace gates the final
release of dma_chan_dev objects.
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