* RE: Question about the function,ni_stc_dma_channel_select_bitfield
[not found] ` <554A1FC3.3000409@gmail.com>
@ 2015-05-06 15:45 ` Hartley Sweeten
2015-05-06 19:09 ` Greg KH
1 sibling, 0 replies; 3+ messages in thread
From: Hartley Sweeten @ 2015-05-06 15:45 UTC (permalink / raw)
To: nick, Ian Abbott
Cc: gregkh@linuxfoundation.org, chase.southwood@gmail.com,
ebru.akagunduz@gmail.com, devel@driverdev.osuosl.org,
linux-kernel@vger.kernel.org
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On Wednesday, May 06, 2015 7:06 AM, nick wrote:
> On 2015-05-06 05:10 AM, Ian Abbott wrote:
>> On 06/05/15 01:22, nick wrote:
>>> Greetings All,
>>> I am wondering if in the function,ni_stc_dma_channel_select_bitfield the line:
>>> return 1 << channel;
>>> is guaranteed to be below the threshold that guarantees us to not overflow on
>>> a unsigned 32 integer due to bit wise shifting to the left.
>>> Thanks Nick
>>>
>>
>> if (channel < 4)
>> return 1 << channel;
>>
>> So, yes.
>>
> This should be commented in my option as this is not common knowledge
> unless you known the hardware specs really well. If I should send in
> a patch adding a comment here please let me known.
A comment is not necessary. The code explicitly states that channel (an unsigned var)
needs to be < 4 for the bit shift to happen.
Hartley
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: Question about the function,ni_stc_dma_channel_select_bitfield
[not found] ` <554A1FC3.3000409@gmail.com>
2015-05-06 15:45 ` Hartley Sweeten
@ 2015-05-06 19:09 ` Greg KH
1 sibling, 0 replies; 3+ messages in thread
From: Greg KH @ 2015-05-06 19:09 UTC (permalink / raw)
To: nick
Cc: Ian Abbott, hsweeten, chase.southwood, ebru.akagunduz, devel,
linux-kernel
On Wed, May 06, 2015 at 10:05:55AM -0400, nick wrote:
> On 2015-05-06 05:10 AM, Ian Abbott wrote:
> > On 06/05/15 01:22, nick wrote:
> >> Greetings All,
> >> I am wondering if in the function,ni_stc_dma_channel_select_bitfield the line:
> >> return 1 << channel;
> >> is guaranteed to be below the threshold that guarantees us to not overflow on
> >> a unsigned 32 integer due to bit wise shifting to the left.
> >> Thanks Nick
> >>
> >
> > if (channel < 4)
> > return 1 << channel;
> >
> > So, yes.
> >
> This should be commented in my option as this is not common knowledge
> unless you known the hardware specs really well. If I should send in
> a patch adding a comment here please let me known.
Nick, this is one reason why you were banned from all vger.kernel.org
mailing lists. You are wasting people's time and refuse to listen to
others.
I do give you credit for coming up with very strange questions that show
a complete lack of understanding of the C language, that is intertaining
at times, like this response, nice job with that.
Please everyone, just add him to your killfile and ignore him, it makes
life much easier these days when he tries to go around the vger ban by
emailing developers directly as he did here.
greg k-h
^ permalink raw reply [flat|nested] 3+ messages in thread