linux-kernel - Re: [PATCH 1/2] usbip: fix off-by-one frame number calculation

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Date:   Tue, 7 Nov 2017 14:10:31 -0700
From:   Shuah Khan <shuah@...nel.org>
To:     Krzysztof Opasiak <k.opasiak@...sung.com>,
        Arnd Bergmann <arnd@...db.de>,
        Valentina Manea <valentina.manea.m@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Johan Hovold <johan@...nel.org>, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] usbip: fix off-by-one frame number calculation

On 11/07/2017 04:21 AM, Krzysztof Opasiak wrote:
> 
> 
> On 11/07/2017 11:39 AM, Arnd Bergmann wrote:
>> vgadget_get_frame returns a frame number from 0 to 2046, which
>> may require an expensive division operation to wrap at one lower
>> than the usual number.
>>
>> I can't see any reason for this, and all other drivers wrap at
>> a power-of-two number. My best explanation is that it was a simple
>> typo, so I'm changing the % modulo operator into a cheaper bitmask
>> that the other drivers use, to make it wrap after 0x7ff rather than
>> before it.
>>
>> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> 
> Looks good to me:
> Reviewed-by: Krzysztof Opasiak <k.opasiak@...sung.com>
> 

Acked-by: Shuah Khan <shuahkh@....samsung.com>

thanks,
-- Shuah