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Message-ID: <5203F4D4.8090609@iki.fi>
Date: Thu, 08 Aug 2013 22:43:16 +0300
From: Jussi Kivilinna <jussi.kivilinna@....fi>
To: Petko Manolov <petkan@...leusys.com>
CC: netdev@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-usb@...r.kernel.org, "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH] net/usb: rtl8150: allocate URB transfer_buffer and setup_packet
separately
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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