Re: [patch] staging: comedi: comedi_bond: silence a shift wrapping warning

[Ian Abbott <abbotti@mev.co.uk>]

On 2013-08-21 21:08, Dan Carpenter wrote:
> On Wed, Aug 21, 2013 at 05:44:34PM +0100, Ian Abbott wrote:
>> On 2013-08-21 13:45, Dan Carpenter wrote:
>>> On Wed, Aug 21, 2013 at 11:50:22AM +0100, Ian Abbott wrote:
>>>> On 2013-08-21 09:27, Dan Carpenter wrote:
>>>>> We set this using:
>>>>>
>>>>> 	devs_closed |= (0x1 << bdev->minor)
>>>>>
>>>>> Since 0x1 is an int then only the lower 32 bits are usable before we hit
>>>>> a shift wrapping bug.  There are some static checkers which complain
>>>>> about this.  I've silenced the warning by making devs_closed a 32 bit
>>>>> number.
>>>>>
>>>>> 32 bits should be enough for anybody.
>>>>
>>>> Not really, as bdev->minor will be in the range 0 to 47 inclusive (0
>>>> to COMEDI_NUM_BOARD_MINORS-1).  Of course, an unsigned long is
>>>> insufficient too on a 32-bit system.
>>>
>>> Ok.  I'll make it a u64 in a v2 patch.
>>
>> If you want, we could drop that, and I could rework it to use
>> DECLARE_BITMAP() and the functions in <linux/bitmap.h> to avoid
>> assuming COMEDI_NUM_BOARD_MINORS is <= 64.  The devs_opened[] in
>> doDevConfig() could also be replaced by a bitmap (it's currently an
>> array of pointers!).
>>
>
> Sure.  Let's drop it then.

Okay, let's drop it.  I have a series of 13 patches to apply to this 
driver to tidy it up a bit and fix various bugs.  I'll send them 
tomorrow after a bit of testing.

-- 
-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti@mev.co.uk>        )=-
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