On Thu, 23 May 2019 21:20:35 +0300
Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx> wrote:
> +static struct page *cpsw_alloc_page(struct cpsw_common *cpsw)
> +{
> + struct page_pool *pool = cpsw->rx_page_pool;
> + struct page *page, *prev_page = NULL;
> + int try = pool->p.pool_size << 2;
> + int start_free = 0, ret;
> +
> + do {
> + page = page_pool_dev_alloc_pages(pool);
> + if (!page)
> + return NULL;
> +
> + /* if netstack has page_pool recycling remove the rest */
> + if (page_ref_count(page) == 1)
> + break;
> +
> + /* start free pages in use, shouldn't happen */
> + if (prev_page == page || start_free) {
> + /* dma unmap/puts page if rfcnt != 1 */
> + page_pool_recycle_direct(pool, page);
> + start_free = 1;
> + continue;
> + }
> +
> + /* if refcnt > 1, page has been holding by netstack, it's pity,
> + * so put it to the ring to be consumed later when fast cash is
> + * empty. If ring is full then free page by recycling as above.
> + */
> + ret = ptr_ring_produce(&pool->ring, page);
This looks very wrong to me! First of all you are manipulation
directly with the internal pool->ring and not using the API, which
makes this code un-maintainable. Second this is wrong, as page_pool
assume the in-variance that pages on the ring have refcnt==1.
> + if (ret) {
> + page_pool_recycle_direct(pool, page);
> + continue;
> + }
> +
> + if (!prev_page)
> + prev_page = page;
> + } while (try--);
> +
> + return page;
> +}
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
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