diff options
Diffstat (limited to 'lib/sbitmap.c')
| -rw-r--r-- | lib/sbitmap.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/lib/sbitmap.c b/lib/sbitmap.c index c07e3cd82e29..4d188d05db15 100644 --- a/lib/sbitmap.c +++ b/lib/sbitmap.c @@ -307,7 +307,22 @@ static int __sbitmap_get_shallow(struct sbitmap *sb, return sbitmap_find_bit(sb, shallow_depth, index, alloc_hint, true); } -int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth) +/** + * sbitmap_get_shallow() - Try to allocate a free bit from a &struct sbitmap, + * limiting the depth used from each word. + * @sb: Bitmap to allocate from. + * @shallow_depth: The maximum number of bits to allocate from the bitmap. + * + * This rather specific operation allows for having multiple users with + * different allocation limits. E.g., there can be a high-priority class that + * uses sbitmap_get() and a low-priority class that uses sbitmap_get_shallow() + * with a @shallow_depth of (sb->depth >> 1). Then, the low-priority + * class can only allocate half of the total bits in the bitmap, preventing it + * from starving out the high-priority class. + * + * Return: Non-negative allocated bit number if successful, -1 otherwise. + */ +static int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth) { int nr; unsigned int hint, depth; @@ -322,7 +337,6 @@ int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth) return nr; } -EXPORT_SYMBOL_GPL(sbitmap_get_shallow); bool sbitmap_any_bit_set(const struct sbitmap *sb) { |