From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Abbott Date: Wed, 21 Aug 2013 16:44:34 +0000 Subject: Re: [patch] staging: comedi: comedi_bond: silence a shift wrapping warning Message-Id: <5214EE72.7090006@mev.co.uk> List-Id: References: <20130821082727.GB5240@elgon.mountain> In-Reply-To: <20130821082727.GB5240@elgon.mountain> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kernel-janitors@vger.kernel.org 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 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!). -- -=( Ian Abbott @ MEV Ltd. E-mail: )=- -=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=-