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Subject: Re: [RFC][PATCH] kernel.h: Add generic roundup_64() macro
To:     Steven Rostedt <rostedt@goodmis.org>,
        Roger Willcocks <roger@filmlight.ltd.uk>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Ben Skeggs <bskeggs@redhat.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Leon Romanovsky <leon@kernel.org>,
        Doug Ledford <dledford@redhat.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        "Darrick J. Wong" <darrick.wong@oracle.com>,
        linux-xfs@vger.kernel.org,
        dri-devel <dri-devel@lists.freedesktop.org>,
        nouveau@lists.freedesktop.org,
        linux-rdma <linux-rdma@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
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From:   Nikolay Borisov <nborisov@suse.com>
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Date:   Fri, 24 May 2019 19:30:45 +0300
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On 24.05.19 г. 18:26 ч., Steven Rostedt wrote:
> On Fri, 24 May 2019 16:11:14 +0100
> Roger Willcocks <roger@filmlight.ltd.uk> wrote:
> 
>> On 23/05/2019 16:27, Steven Rostedt wrote:
>>>
>>> I haven't yet tested this, but what about something like the following:
>>>
>>> ...perhaps forget about the constant check, and just force
>>> the power of two check:
>>>
>>> 							\
>>> 	if (!(__y & (__y >> 1))) {			\
>>> 		__x = round_up(x, y);			\
>>> 	} else {					\  
>>
>> You probably want
>>
>>             if (!(__y & (__y - 1))
>>
>> --
> 
> Yes I do. I corrected it in my next email.
> 
>  http://lkml.kernel.org/r/20190523133648.591f9e78@gandalf.local.home

Or perhaps just using is_power_of_2 from include/linux/log2.h ?
> 
>> #define roundup(x, y) (					\
>> {							\
>> 	typeof(y) __y = y;				\
>> 	typeof(x) __x;					\
>> 							\
>> 	if (__y & (__y - 1))				\
>> 		__x = round_up(x, __y);			\
>> 	else						\
>> 		__x = (((x) + (__y - 1)) / __y) * __y;	\
>> 	__x;						\
>> })
> 
> 
> -- Steve
>