Subject: Re: [PATCH] net/usb: rtl8150: allocate URB transfer_buffer and setup_packet separately

From: Jussi Kivilinna <[email-masked]>
Date: Thu, 08 Aug 2013 22:43:16 +0300

On 08.08.2013 18:14, Petko Manolov wrote:
> On Wed, 7 Aug 2013, Jussi Kivilinna wrote:
> 
>> rtl8150 allocates URB transfer_buffer and setup_packet as part of same 
>> structure 'struct async_req'. This can cause same cacheline to be 
>> DMA-mapped twice with same URB. This can lead to memory corruption on 
>> some systems.
> 
> I can see performance impact due to the double mapping.  However, memory 
> corruption seems a bit too much for sane cache and DMA controllers.  Out 
> of interest - which is the architecture that will potentially corrupt the 
> memory.

rtlwifi driver had similar structure to allocate both setup_packet and transfer_buffer in single go (overlapping dma-mapping cachelines) and this caused problems on ARM/sunxi. Problems means: memory corruptions at random locations, device freezes and lock-ups.

-Jussi

> cheers,
> Petko

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