Re: [PATCH 0/6] get rid of on-stack dma buffers

From: Florian Mickler
Date: Tue Mar 22 2011 - 10:27:40 EST

2011/3/22 Roedel, Joerg <Joerg.Roedel@xxxxxxx>:
> On Mon, Mar 21, 2011 at 05:03:15PM -0400, Florian Mickler wrote:
>> I guess (not verified), that the dma api takes sufficient precautions
>> to abort the dma transfer if a timeout happens.  So freeing _should_
>> not be an issue. (At least, I would expect big fat warnings everywhere
>> if that were the case)
> Freeing is very well an issue. All you can expect from the DMA-API is to
> give you a valid DMA handle for your device. But it can not prevent that
> a device uses this handle after you returned it. You need to make sure
> yourself that any pending DMA is canceled before calling kfree().

sorry, I meant usb_control_msg above when I said 'dma api'... as that
is the function these
drivers use to do the dma.

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