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

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

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!).

-- 
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