Re: [PATCH 01/10] lib/sort: Add priv pointer to swap function

[Masami Hiramatsu <mhiramat@kernel.org>]

On Tue, 22 Feb 2022 18:05:51 +0100
Jiri Olsa <jolsa@kernel.org> wrote:

> Adding support to have priv pointer in swap callback function.
> 
> Following the initial change on cmp callback functions [1]
> and adding SWAP_WRAPPER macro to identify sort call of sort_r.
> 

This looks good to me.

Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>

Thank you,

> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> [1] 4333fb96ca10 ("media: lib/sort.c: implement sort() variant taking context argument")
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  include/linux/sort.h  |  2 +-
>  include/linux/types.h |  1 +
>  lib/sort.c            | 40 ++++++++++++++++++++++++++++++----------
>  3 files changed, 32 insertions(+), 11 deletions(-)
> 
> diff --git a/include/linux/sort.h b/include/linux/sort.h
> index b5898725fe9d..e163287ac6c1 100644
> --- a/include/linux/sort.h
> +++ b/include/linux/sort.h
> @@ -6,7 +6,7 @@
>  
>  void sort_r(void *base, size_t num, size_t size,
>  	    cmp_r_func_t cmp_func,
> -	    swap_func_t swap_func,
> +	    swap_r_func_t swap_func,
>  	    const void *priv);
>  
>  void sort(void *base, size_t num, size_t size,
> diff --git a/include/linux/types.h b/include/linux/types.h
> index ac825ad90e44..ea8cf60a8a79 100644
> --- a/include/linux/types.h
> +++ b/include/linux/types.h
> @@ -226,6 +226,7 @@ struct callback_head {
>  typedef void (*rcu_callback_t)(struct rcu_head *head);
>  typedef void (*call_rcu_func_t)(struct rcu_head *head, rcu_callback_t func);
>  
> +typedef void (*swap_r_func_t)(void *a, void *b, int size, const void *priv);
>  typedef void (*swap_func_t)(void *a, void *b, int size);
>  
>  typedef int (*cmp_r_func_t)(const void *a, const void *b, const void *priv);
> diff --git a/lib/sort.c b/lib/sort.c
> index aa18153864d2..b399bf10d675 100644
> --- a/lib/sort.c
> +++ b/lib/sort.c
> @@ -122,16 +122,27 @@ static void swap_bytes(void *a, void *b, size_t n)
>   * a pointer, but small integers make for the smallest compare
>   * instructions.
>   */
> -#define SWAP_WORDS_64 (swap_func_t)0
> -#define SWAP_WORDS_32 (swap_func_t)1
> -#define SWAP_BYTES    (swap_func_t)2
> +#define SWAP_WORDS_64 (swap_r_func_t)0
> +#define SWAP_WORDS_32 (swap_r_func_t)1
> +#define SWAP_BYTES    (swap_r_func_t)2
> +#define SWAP_WRAPPER  (swap_r_func_t)3
> +
> +struct wrapper {
> +	cmp_func_t cmp;
> +	swap_func_t swap;
> +};
>  
>  /*
>   * The function pointer is last to make tail calls most efficient if the
>   * compiler decides not to inline this function.
>   */
> -static void do_swap(void *a, void *b, size_t size, swap_func_t swap_func)
> +static void do_swap(void *a, void *b, size_t size, swap_r_func_t swap_func, const void *priv)
>  {
> +	if (swap_func == SWAP_WRAPPER) {
> +		((const struct wrapper *)priv)->swap(a, b, (int)size);
> +		return;
> +	}
> +
>  	if (swap_func == SWAP_WORDS_64)
>  		swap_words_64(a, b, size);
>  	else if (swap_func == SWAP_WORDS_32)
> @@ -139,7 +150,7 @@ static void do_swap(void *a, void *b, size_t size, swap_func_t swap_func)
>  	else if (swap_func == SWAP_BYTES)
>  		swap_bytes(a, b, size);
>  	else
> -		swap_func(a, b, (int)size);
> +		swap_func(a, b, (int)size, priv);
>  }
>  
>  #define _CMP_WRAPPER ((cmp_r_func_t)0L)
> @@ -147,7 +158,7 @@ static void do_swap(void *a, void *b, size_t size, swap_func_t swap_func)
>  static int do_cmp(const void *a, const void *b, cmp_r_func_t cmp, const void *priv)
>  {
>  	if (cmp == _CMP_WRAPPER)
> -		return ((cmp_func_t)(priv))(a, b);
> +		return ((const struct wrapper *)priv)->cmp(a, b);
>  	return cmp(a, b, priv);
>  }
>  
> @@ -198,7 +209,7 @@ static size_t parent(size_t i, unsigned int lsbit, size_t size)
>   */
>  void sort_r(void *base, size_t num, size_t size,
>  	    cmp_r_func_t cmp_func,
> -	    swap_func_t swap_func,
> +	    swap_r_func_t swap_func,
>  	    const void *priv)
>  {
>  	/* pre-scale counters for performance */
> @@ -208,6 +219,10 @@ void sort_r(void *base, size_t num, size_t size,
>  	if (!a)		/* num < 2 || size == 0 */
>  		return;
>  
> +	/* called from 'sort' without swap function, let's pick the default */
> +	if (swap_func == SWAP_WRAPPER && !((struct wrapper *)priv)->swap)
> +		swap_func = NULL;
> +
>  	if (!swap_func) {
>  		if (is_aligned(base, size, 8))
>  			swap_func = SWAP_WORDS_64;
> @@ -230,7 +245,7 @@ void sort_r(void *base, size_t num, size_t size,
>  		if (a)			/* Building heap: sift down --a */
>  			a -= size;
>  		else if (n -= size)	/* Sorting: Extract root to --n */
> -			do_swap(base, base + n, size, swap_func);
> +			do_swap(base, base + n, size, swap_func, priv);
>  		else			/* Sort complete */
>  			break;
>  
> @@ -257,7 +272,7 @@ void sort_r(void *base, size_t num, size_t size,
>  		c = b;			/* Where "a" belongs */
>  		while (b != a) {	/* Shift it into place */
>  			b = parent(b, lsbit, size);
> -			do_swap(base + b, base + c, size, swap_func);
> +			do_swap(base + b, base + c, size, swap_func, priv);
>  		}
>  	}
>  }
> @@ -267,6 +282,11 @@ void sort(void *base, size_t num, size_t size,
>  	  cmp_func_t cmp_func,
>  	  swap_func_t swap_func)
>  {
> -	return sort_r(base, num, size, _CMP_WRAPPER, swap_func, cmp_func);
> +	struct wrapper w = {
> +		.cmp  = cmp_func,
> +		.swap = swap_func,
> +	};
> +
> +	return sort_r(base, num, size, _CMP_WRAPPER, SWAP_WRAPPER, &w);
>  }
>  EXPORT_SYMBOL(sort);
> -- 
> 2.35.1
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>