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

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Message-ID: <ce10214c-84ac-438a-ac0b-d876e322b2f6@intel.com>
Date: Wed, 14 May 2025 13:19:38 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Fenghua Yu <fenghuay@...dia.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 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/