diff mbox series

[v2,03/35] lib/sbitmap; make __sbitmap_get_word() using find_and_set_bit()

Message ID 20231203193307.542794-2-yury.norov@gmail.com
State New
Headers
Series bitops: add atomic find_bit() operations |

Commit Message

Yury Norov Dec. 3, 2023, 7:32 p.m. UTC 
  __sbitmap_get_word() opencodes either find_and_set_bit_wrap(), or
find_and_set_next_bit() depending on hint and wrap parameters.

Switch it to use the atomic find_bit() API. While here, simplify
sbitmap_find_bit_in_word(), which calls it.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 lib/sbitmap.c | 46 ++++++++--------------------------------------
 1 file changed, 8 insertions(+), 38 deletions(-)

Comments

Jan Kara Dec. 4, 2023, 6:22 p.m. UTC | #1 
On Sun 03-12-23 11:32:35, Yury Norov wrote:
> __sbitmap_get_word() opencodes either find_and_set_bit_wrap(), or
> find_and_set_next_bit() depending on hint and wrap parameters.
> 
> Switch it to use the atomic find_bit() API. While here, simplify
> sbitmap_find_bit_in_word(), which calls it.
> 
> Signed-off-by: Yury Norov <yury.norov@gmail.com>

Looks good to me. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  lib/sbitmap.c | 46 ++++++++--------------------------------------
>  1 file changed, 8 insertions(+), 38 deletions(-)
> 
> diff --git a/lib/sbitmap.c b/lib/sbitmap.c
> index d0a5081dfd12..b21aebd07fd6 100644
> --- a/lib/sbitmap.c
> +++ b/lib/sbitmap.c
> @@ -133,38 +133,11 @@ void sbitmap_resize(struct sbitmap *sb, unsigned int depth)
>  }
>  EXPORT_SYMBOL_GPL(sbitmap_resize);
>  
> -static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
> +static inline int __sbitmap_get_word(unsigned long *word, unsigned long depth,
>  			      unsigned int hint, bool wrap)
>  {
> -	int nr;
> -
> -	/* don't wrap if starting from 0 */
> -	wrap = wrap && hint;
> -
> -	while (1) {
> -		nr = find_next_zero_bit(word, depth, hint);
> -		if (unlikely(nr >= depth)) {
> -			/*
> -			 * We started with an offset, and we didn't reset the
> -			 * offset to 0 in a failure case, so start from 0 to
> -			 * exhaust the map.
> -			 */
> -			if (hint && wrap) {
> -				hint = 0;
> -				continue;
> -			}
> -			return -1;
> -		}
> -
> -		if (!test_and_set_bit_lock(nr, word))
> -			break;
> -
> -		hint = nr + 1;
> -		if (hint >= depth - 1)
> -			hint = 0;
> -	}
> -
> -	return nr;
> +	return wrap ? find_and_set_bit_wrap_lock(word, depth, hint) :
> +			find_and_set_next_bit_lock(word, depth, hint);
>  }
>  
>  static int sbitmap_find_bit_in_word(struct sbitmap_word *map,
> @@ -175,15 +148,12 @@ static int sbitmap_find_bit_in_word(struct sbitmap_word *map,
>  	int nr;
>  
>  	do {
> -		nr = __sbitmap_get_word(&map->word, depth,
> -					alloc_hint, wrap);
> -		if (nr != -1)
> -			break;
> -		if (!sbitmap_deferred_clear(map))
> -			break;
> -	} while (1);
> +		nr = __sbitmap_get_word(&map->word, depth, alloc_hint, wrap);
> +		if (nr < depth)
> +			return nr;
> +	} while (sbitmap_deferred_clear(map));
>  
> -	return nr;
> +	return -1;
>  }
>  
>  static int sbitmap_find_bit(struct sbitmap *sb,
> -- 
> 2.40.1
>
Jens Axboe Dec. 4, 2023, 6:40 p.m. UTC | #2 
On 12/3/23 12:32 PM, Yury Norov wrote:
> diff --git a/lib/sbitmap.c b/lib/sbitmap.c
> index d0a5081dfd12..b21aebd07fd6 100644
> --- a/lib/sbitmap.c
> +++ b/lib/sbitmap.c
> @@ -133,38 +133,11 @@ void sbitmap_resize(struct sbitmap *sb, unsigned int depth)
>  }
>  EXPORT_SYMBOL_GPL(sbitmap_resize);
>  
> -static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
> +static inline int __sbitmap_get_word(unsigned long *word, unsigned long depth,
>  			      unsigned int hint, bool wrap)
>  {
> -	int nr;
> -
> -	/* don't wrap if starting from 0 */
> -	wrap = wrap && hint;
> -
> -	while (1) {
> -		nr = find_next_zero_bit(word, depth, hint);
> -		if (unlikely(nr >= depth)) {
> -			/*
> -			 * We started with an offset, and we didn't reset the
> -			 * offset to 0 in a failure case, so start from 0 to
> -			 * exhaust the map.
> -			 */
> -			if (hint && wrap) {
> -				hint = 0;
> -				continue;
> -			}
> -			return -1;
> -		}
> -
> -		if (!test_and_set_bit_lock(nr, word))
> -			break;
> -
> -		hint = nr + 1;
> -		if (hint >= depth - 1)
> -			hint = 0;
> -	}
> -
> -	return nr;
> +	return wrap ? find_and_set_bit_wrap_lock(word, depth, hint) :
> +			find_and_set_next_bit_lock(word, depth, hint);
>  }

Please make this:

	if (wrap)
		return find_and_set_bit_wrap_lock(word, depth, hint) :
	return find_and_set_next_bit_lock(word, depth, hint);

so this is a lot more readable.
diff mbox series

Patch

diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index d0a5081dfd12..b21aebd07fd6 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -133,38 +133,11 @@  void sbitmap_resize(struct sbitmap *sb, unsigned int depth)
 }
 EXPORT_SYMBOL_GPL(sbitmap_resize);
 
-static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
+static inline int __sbitmap_get_word(unsigned long *word, unsigned long depth,
 			      unsigned int hint, bool wrap)
 {
-	int nr;
-
-	/* don't wrap if starting from 0 */
-	wrap = wrap && hint;
-
-	while (1) {
-		nr = find_next_zero_bit(word, depth, hint);
-		if (unlikely(nr >= depth)) {
-			/*
-			 * We started with an offset, and we didn't reset the
-			 * offset to 0 in a failure case, so start from 0 to
-			 * exhaust the map.
-			 */
-			if (hint && wrap) {
-				hint = 0;
-				continue;
-			}
-			return -1;
-		}
-
-		if (!test_and_set_bit_lock(nr, word))
-			break;
-
-		hint = nr + 1;
-		if (hint >= depth - 1)
-			hint = 0;
-	}
-
-	return nr;
+	return wrap ? find_and_set_bit_wrap_lock(word, depth, hint) :
+			find_and_set_next_bit_lock(word, depth, hint);
 }
 
 static int sbitmap_find_bit_in_word(struct sbitmap_word *map,
@@ -175,15 +148,12 @@  static int sbitmap_find_bit_in_word(struct sbitmap_word *map,
 	int nr;
 
 	do {
-		nr = __sbitmap_get_word(&map->word, depth,
-					alloc_hint, wrap);
-		if (nr != -1)
-			break;
-		if (!sbitmap_deferred_clear(map))
-			break;
-	} while (1);
+		nr = __sbitmap_get_word(&map->word, depth, alloc_hint, wrap);
+		if (nr < depth)
+			return nr;
+	} while (sbitmap_deferred_clear(map));
 
-	return nr;
+	return -1;
 }
 
 static int sbitmap_find_bit(struct sbitmap *sb,