Re: [PATCH v5 7/8] cpumask: Mark functions as pure

[Peter Zijlstra]

On Tue, Feb 09, 2021 at 02:16:52PM -0800, Nadav Amit wrote:

> @@ -235,7 +235,7 @@ static inline unsigned int cpumask_last(const struct 
> cpumask *srcp)
>   return find_last_bit(cpumask_bits(srcp), nr_cpumask_bits);
>  }
>  
> -unsigned int cpumask_next(int n, const struct cpumask *srcp);
> +unsigned int __pure cpumask_next(int n, const struct cpumask *srcp);
>  
>  /**
>   * cpumask_next_zero - get the next unset cpu in a cpumask

I've changed it to:

__pure unsigned int cpumask_next(...);

to be consistent with these:

> @@ -252,8 +252,8 @@ static inline unsigned int cpumask_next_zero(int n, const 
> struct cpumask *srcp)
>   return find_next_zero_bit(cpumask_bits(srcp), nr_cpumask_bits, n+1);
>  }
>  
> -int cpumask_next_and(int n, const struct cpumask *, const struct cpumask *);
> -int cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
> +__pure int cpumask_next_and(int n, const struct cpumask *, const struct 
> cpumask *);
> +__pure int cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
>  unsigned int cpumask_local_spread(unsigned int i, int node);
>  int cpumask_any_and_distribute(const struct cpumask *src1p,
>  const struct cpumask *src2p);

[PATCH v5 7/8] cpumask: Mark functions as pure

[Nadav Amit]

From: Nadav Amit 

cpumask_next_and() and cpumask_any_but() are pure, and marking them as
such seems to generate different and presumably better code for
native_flush_tlb_multi().

Reviewed-by: Dave Hansen 
Signed-off-by: Nadav Amit 
---
 include/linux/cpumask.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 383684e30f12..e86b7d027cfb 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -235,7 +235,7 @@ static inline unsigned int cpumask_last(const struct 
cpumask *srcp)
return find_last_bit(cpumask_bits(srcp), nr_cpumask_bits);
 }
 
-unsigned int cpumask_next(int n, const struct cpumask *srcp);
+unsigned int __pure cpumask_next(int n, const struct cpumask *srcp);
 
 /**
  * cpumask_next_zero - get the next unset cpu in a cpumask
@@ -252,8 +252,8 @@ static inline unsigned int cpumask_next_zero(int n, const 
struct cpumask *srcp)
return find_next_zero_bit(cpumask_bits(srcp), nr_cpumask_bits, n+1);
 }
 
-int cpumask_next_and(int n, const struct cpumask *, const struct cpumask *);
-int cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
+__pure int cpumask_next_and(int n, const struct cpumask *, const struct 
cpumask *);
+__pure int cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
 unsigned int cpumask_local_spread(unsigned int i, int node);
 int cpumask_any_and_distribute(const struct cpumask *src1p,
   const struct cpumask *src2p);
-- 
2.25.1