linux-kernel - Re: [PATCH v11 02/30] find: add find_first_andnot

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Message-ID: <e2b35d83-4347-4502-a76b-107f92f6a3a2@nvidia.com>
Date: Wed, 14 May 2025 16:20:18 -0700
From: Fenghua Yu <fenghuay@...dia.com>
To: Reinette Chatre <reinette.chatre@...el.com>,
 James Morse <james.morse@....com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, H Peter Anvin <hpa@...or.com>,
 Babu Moger <Babu.Moger@....com>, shameerali.kolothum.thodi@...wei.com,
 D Scott Phillips OS <scott@...amperecomputing.com>,
 carl@...amperecomputing.com, lcherian@...vell.com,
 bobo.shaobowang@...wei.com, tan.shaopeng@...itsu.com,
 baolin.wang@...ux.alibaba.com, Jamie Iles <quic_jiles@...cinc.com>,
 Xin Hao <xhao@...ux.alibaba.com>, peternewman@...gle.com,
 dfustini@...libre.com, amitsinght@...vell.com,
 David Hildenbrand <david@...hat.com>, Rex Nie <rex.nie@...uarmicro.com>,
 Dave Martin <dave.martin@....com>, Koba Ko <kobak@...dia.com>,
 Shanker Donthineni <sdonthineni@...dia.com>,
 "Yury Norov [NVIDIA]" <yury.norov@...il.com>
Subject: Re: [PATCH v11 02/30] find: add find_first_andnot_bit()

Hi, Reinette,

On 5/14/25 13:19, Reinette Chatre wrote:
> Hi Fenghua,
>
> On 5/14/25 12:59 PM, Fenghua Yu wrote:
>> Hi, James and Yury,
>>
>> On 5/13/25 10:15, James Morse wrote:
>>> From: "Yury Norov [NVIDIA]" <yury.norov@...il.com>
>>>
>>> The function helps to implement cpumask_andnot() APIs.
>>>
>>> Tested-by: James Morse <james.morse@....com>
>>> Reviewed-by: James Morse <james.morse@....com>
>>> Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
>>> Signed-off-by: Yury Norov [NVIDIA] <yury.norov@...il.com>
>>> Signed-off-by: James Morse <james.morse@....com>
>>> ---
>>>    include/linux/find.h | 25 +++++++++++++++++++++++++
>>>    lib/find_bit.c       | 11 +++++++++++
>>>    2 files changed, 36 insertions(+)
>>>
>>> diff --git a/include/linux/find.h b/include/linux/find.h
>>> index 68685714bc18..5a2c267ea7f9 100644
>>> --- a/include/linux/find.h
>>> +++ b/include/linux/find.h
>>> @@ -29,6 +29,8 @@ unsigned long __find_nth_and_andnot_bit(const unsigned long *addr1, const unsign
>>>                        unsigned long n);
>>>    extern unsigned long _find_first_and_bit(const unsigned long *addr1,
>>>                         const unsigned long *addr2, unsigned long size);
>>> +unsigned long _find_first_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
>>> +                 unsigned long size);
>>>    unsigned long _find_first_and_and_bit(const unsigned long *addr1, const unsigned long *addr2,
>>>                          const unsigned long *addr3, unsigned long size);
>>>    extern unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size);
>>> @@ -347,6 +349,29 @@ unsigned long find_first_and_bit(const unsigned long *addr1,
>>>    }
>>>    #endif
>>>    +/**
>>> + * find_first_andnot_bit - find the first bit set in 1st memory region and unset in 2nd
>>> + * @addr1: The first address to base the search on
>>> + * @addr2: The second address to base the search on
>>> + * @size: The bitmap size in bits
>>> + *
>>> + * Returns the bit number for the first set bit
>>> + * If no bits are set, returns >= @size.
>>> + */
>>> +static __always_inline
>>> +unsigned long find_first_andnot_bit(const unsigned long *addr1,
>>> +                 const unsigned long *addr2,
>>> +                 unsigned long size)
>> CHECK: Alignment should match open parenthesis
>>
> This was brought up [2] during review of V1 of this specific work [1].
>
> Please compare this code to the rest of the file. Specifically, this
> alignment guidance is not adhered to in this file. In this contribution
> we thus accept the contribution from bitmap API maintainer (Yury) without
> dictating how formatting should be done.
>
> Reinette
>
> [1] https://lore.kernel.org/all/20250407153856.133093-1-yury.norov@gmail.com/
> [2] https://lore.kernel.org/all/062e5e61-e2c3-418e-987b-33fd9009d03f@intel.com/
>
Thanks for the info. This check is acceptable here. I already put my 
Reviewed-by on this patch.

-Fenghua