linux-kernel - Re: [PATCH v2 1/7] cpumask: introduce cpumask_first_and

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Date: Tue, 16 Apr 2024 10:49:46 -0700
From: Yury Norov <yury.norov@...il.com>
To: Dawei Li <dawei.li@...ngroup.cn>
Cc: tglx@...utronix.de, rafael@...nel.org, akpm@...ux-foundation.org,
	maz@...nel.org, florian.fainelli@...adcom.com,
	chenhuacai@...nel.org, jiaxun.yang@...goat.com, anup@...infault.org,
	palmer@...belt.com, samuel.holland@...ive.com,
	linux@...musvillemoes.dk, daniel.lezcano@...aro.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/7] cpumask: introduce cpumask_first_and_and()

On Tue, Apr 16, 2024 at 10:45:54AM -0700, Yury Norov wrote:
> On Tue, Apr 16, 2024 at 04:54:48PM +0800, Dawei Li wrote:
> > Introduce cpumask_first_and_and() to get intersection between 3 cpumasks,
> > free of any intermediate cpumask variable. Instead, cpumask_first_and_and()
> > works in-place with all inputs and produce desired output directly.

Still there: s/produce/produces

But whatever. Also, I think this patch would better go with the rest
of the series, right?

> > 
> > Signed-off-by: Dawei Li <dawei.li@...ngroup.cn>
> 
> Acked-by: Yury Norov <yury.norov@...il.com>
> 
> > ---
> >  include/linux/cpumask.h | 17 +++++++++++++++++
> >  include/linux/find.h    | 27 +++++++++++++++++++++++++++
> >  lib/find_bit.c          | 12 ++++++++++++
> >  3 files changed, 56 insertions(+)
> > 
> > diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
> > index 1c29947db848..c46f9e9e1d66 100644
> > --- a/include/linux/cpumask.h
> > +++ b/include/linux/cpumask.h
> > @@ -187,6 +187,23 @@ unsigned int cpumask_first_and(const struct cpumask *srcp1, const struct cpumask
> >  	return find_first_and_bit(cpumask_bits(srcp1), cpumask_bits(srcp2), small_cpumask_bits);
> >  }
> >  
> > +/**
> > + * cpumask_first_and_and - return the first cpu from *srcp1 & *srcp2 & *srcp3
> > + * @srcp1: the first input
> > + * @srcp2: the second input
> > + * @srcp3: the third input
> > + *
> > + * Return: >= nr_cpu_ids if no cpus set in all.
> > + */
> > +static inline
> > +unsigned int cpumask_first_and_and(const struct cpumask *srcp1,
> > +				   const struct cpumask *srcp2,
> > +				   const struct cpumask *srcp3)
> > +{
> > +	return find_first_and_and_bit(cpumask_bits(srcp1), cpumask_bits(srcp2),
> > +				      cpumask_bits(srcp3), small_cpumask_bits);
> > +}
> > +
> >  /**
> >   * cpumask_last - get the last CPU in a cpumask
> >   * @srcp:	- the cpumask pointer
> > diff --git a/include/linux/find.h b/include/linux/find.h
> > index c69598e383c1..28ec5a03393a 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_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);
> >  extern unsigned long _find_last_bit(const unsigned long *addr, unsigned long size);
> >  
> > @@ -345,6 +347,31 @@ unsigned long find_first_and_bit(const unsigned long *addr1,
> >  }
> >  #endif
> >  
> > +/**
> > + * find_first_and_and_bit - find the first set bit in 3 memory regions
> > + * @addr1: The first address to base the search on
> > + * @addr2: The second address to base the search on
> > + * @addr3: The third 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 inline
> > +unsigned long find_first_and_and_bit(const unsigned long *addr1,
> > +				     const unsigned long *addr2,
> > +				     const unsigned long *addr3,
> > +				     unsigned long size)
> > +{
> > +	if (small_const_nbits(size)) {
> > +		unsigned long val = *addr1 & *addr2 & *addr3 & GENMASK(size - 1, 0);
> > +
> > +		return val ? __ffs(val) : size;
> > +	}
> > +
> > +	return _find_first_and_and_bit(addr1, addr2, addr3, size);
> > +}
> > +
> >  #ifndef find_first_zero_bit
> >  /**
> >   * find_first_zero_bit - find the first cleared bit in a memory region
> > diff --git a/lib/find_bit.c b/lib/find_bit.c
> > index 32f99e9a670e..dacadd904250 100644
> > --- a/lib/find_bit.c
> > +++ b/lib/find_bit.c
> > @@ -116,6 +116,18 @@ unsigned long _find_first_and_bit(const unsigned long *addr1,
> >  EXPORT_SYMBOL(_find_first_and_bit);
> >  #endif
> >  
> > +/*
> > + * Find the first set bit in three memory regions.
> > + */
> > +unsigned long _find_first_and_and_bit(const unsigned long *addr1,
> > +				      const unsigned long *addr2,
> > +				      const unsigned long *addr3,
> > +				      unsigned long size)
> > +{
> > +	return FIND_FIRST_BIT(addr1[idx] & addr2[idx] & addr3[idx], /* nop */, size);
> > +}
> > +EXPORT_SYMBOL(_find_first_and_and_bit);
> > +
> >  #ifndef find_first_zero_bit
> >  /*
> >   * Find the first cleared bit in a memory region.
> > -- 
> > 2.27.0