linux-kernel - Re: [RESEND PATCH v5 11/16] lib min_heap: Update min_heap_push() and min_heap

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Date: Wed, 15 May 2024 10:37:55 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Kuan-Wei Chiu <visitorckw@...il.com>
Cc: colyli@...e.de, kent.overstreet@...ux.dev, msakai@...hat.com,
	mingo@...hat.com, acme@...nel.org, namhyung@...nel.org,
	akpm@...ux-foundation.org, bfoster@...hat.com, mark.rutland@....com,
	alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
	irogers@...gle.com, adrian.hunter@...el.com, bagasdotme@...il.com,
	jserv@...s.ncku.edu.tw, linux-bcache@...r.kernel.org,
	linux-kernel@...r.kernel.org, dm-devel@...ts.linux.dev,
	linux-bcachefs@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: Re: [RESEND PATCH v5 11/16] lib min_heap: Update min_heap_push() and
 min_heap_pop() to return bool values

On Tue, May 14, 2024 at 04:47:19PM +0800, Kuan-Wei Chiu wrote:
> Modify the min_heap_push() and min_heap_pop() to return a boolean
> value. They now return false when the operation fails and true when it
> succeeds.

But why ?!

> Signed-off-by: Kuan-Wei Chiu <visitorckw@...il.com>
> Reviewed-by: Ian Rogers <irogers@...gle.com>
> ---
>  include/linux/min_heap.h | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/min_heap.h b/include/linux/min_heap.h
> index c94f9d303205..2d080f85ad0d 100644
> --- a/include/linux/min_heap.h
> +++ b/include/linux/min_heap.h
> @@ -147,18 +147,20 @@ void __min_heapify_all(min_heap_char *heap, size_t elem_size,
>  
>  /* Remove minimum element from the heap, O(log2(nr)). */
>  static __always_inline
> -void __min_heap_pop(min_heap_char *heap, size_t elem_size,
> +bool __min_heap_pop(min_heap_char *heap, size_t elem_size,
>  		const struct min_heap_callbacks *func, void *args)
>  {
>  	void *data = heap->data;
>  
>  	if (WARN_ONCE(heap->nr <= 0, "Popping an empty heap"))
> -		return;
> +		return false;
>  
>  	/* Place last element at the root (position 0) and then sift down. */
>  	heap->nr--;
>  	memcpy(data, data + (heap->nr * elem_size), elem_size);
>  	__min_heapify(heap, 0, elem_size, func, args);
> +
> +	return true;
>  }
>  
>  #define min_heap_pop(_heap, _func, _args)	\
> @@ -184,7 +186,7 @@ void __min_heap_pop_push(min_heap_char *heap,
>  
>  /* Push an element on to the heap, O(log2(nr)). */
>  static __always_inline
> -void __min_heap_push(min_heap_char *heap, const void *element, size_t elem_size,
> +bool __min_heap_push(min_heap_char *heap, const void *element, size_t elem_size,
>  		const struct min_heap_callbacks *func, void *args)
>  {
>  	void *data = heap->data;
> @@ -192,7 +194,7 @@ void __min_heap_push(min_heap_char *heap, const void *element, size_t elem_size,
>  	int pos;
>  
>  	if (WARN_ONCE(heap->nr >= heap->size, "Pushing on a full heap"))
> -		return;
> +		return false;
>  
>  	/* Place at the end of data. */
>  	pos = heap->nr;
> @@ -207,6 +209,8 @@ void __min_heap_push(min_heap_char *heap, const void *element, size_t elem_size,
>  			break;
>  		func->swp(parent, child, args);
>  	}
> +
> +	return true;
>  }
>  
>  #define min_heap_push(_heap, _element, _func, _args)	\
> -- 
> 2.34.1
>