On Fri, Apr 19, 2019 at 11:31:56AM +0300, Ilias Apalodimas wrote:
Hi Ivan,+static struct page *cpsw_alloc_page(struct cpsw_common *cpsw) +{ + struct page_pool *pool = cpsw->rx_page_pool; + struct page *page; + int i = 0; + + do { + page = page_pool_dev_alloc_pages(pool); + if (!page) + return NULL; + + /* skip pages used by skb netstack */I think the comment here is wrong and might confuse people. The page ref cnt is 1, which means the packet was *processed* and netstack is done with it, hence you can re-use it. If it's !=1 then you correctly unmap the buffer and decrease the ref cnt, so it will eventually be freed and not returned to the pool, right?
It's compensation substitution for page_pool support in skb netsack. And should be considered in combine with: skb = build_skb(xmeta, cpsw_rxbuf_total_len(pkt_size)); ... page_pool_recycle_direct(pool, page); page_ref_inc(page); netif_receive_skb(skb); Here order is important. I will correct comments in final version (w/o overloading) ofc, leaving thinking environment for people. I think it's fair enough about this.
+ if (page_ref_count(page) == 1) + break; + + /* it's a pitty, but free page */ + page_pool_recycle_direct(pool, page); + } while (++i < descs_pool_size); + + return page; +} +/Ilias
-- Regards, Ivan Khoronzhuk
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