On Thu, Feb 06, 2025 at 06:50:41PM +0000, Frank van der Linden wrote:
> In addition to the number of allocations and releases, system
> management software may like to be aware of the size of CMA
> areas, and how many pages are available in it. This information
> is currently not available, so export it in total_page and
> available_pages, respectively.
>
> The name 'available_pages' was picked over 'free_pages' because
> 'free' implies that the pages are unused. But they might not
> be, they just haven't been used by cma_alloc
>
> The number of available pages is tracked regardless of
> CONFIG_CMA_SYSFS, allowing for a few minor shortcuts in
> the code, avoiding bitmap operations.
>
> Signed-off-by: Frank van der Linden <fvdl@xxxxxxxxxx>
LGTM,
nit below
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
> ---
...
> @@ -444,6 +445,14 @@ static struct page *__cma_alloc(struct cma *cma, unsigned long count,
>
> for (;;) {
> spin_lock_irq(&cma->lock);
> + /*
> + * If the request is larger than the available number
> + * of pages, stop right away.
> + */
> + if (count > cma->available_count) {
> + spin_unlock_irq(&cma->lock);
> + break;
> + }
> bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap,
> bitmap_maxno, start, bitmap_count, mask,
> offset);
> @@ -452,6 +461,7 @@ static struct page *__cma_alloc(struct cma *cma, unsigned long count,
> break;
> }
> bitmap_set(cma->bitmap, bitmap_no, bitmap_count);
> + cma->available_count -= count;
I wonder whether we should have a cma_bitmat_set, so available_count would be
touched in there.
--
Oscar Salvador
SUSE Labs
