[PATCH mel-git 3/3] net: page_pool: convert to use alloc_pages_bulk_array variant

[Jesper Dangaard Brouer]

Using the API variant alloc_pages_bulk_array from page_pool
was done in a separate patch to ease benchmarking the
variants separately.  Maintainers can squash patch if preferred.

Signed-off-by: Jesper Dangaard Brouer <bro...@redhat.com>
---
 include/net/page_pool.h |    2 +-
 net/core/page_pool.c    |   22 ++++++++++++++++------
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index b5b195305346..6d517a37c18b 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -65,7 +65,7 @@
 #define PP_ALLOC_CACHE_REFILL  64
 struct pp_alloc_cache {
        u32 count;
-       void *cache[PP_ALLOC_CACHE_SIZE];
+       struct page *cache[PP_ALLOC_CACHE_SIZE];
 };
 
 struct page_pool_params {
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 3bf6e7f5fc89..9ec1aa9640ad 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -233,24 +233,34 @@ static struct page *__page_pool_alloc_pages_slow(struct 
page_pool *pool,
        const int bulk = PP_ALLOC_CACHE_REFILL;
        unsigned int pp_flags = pool->p.flags;
        unsigned int pp_order = pool->p.order;
-       struct page *page, *next;
-       LIST_HEAD(page_list);
+       struct page *page;
+       int i, nr_pages;
 
        /* Don't support bulk alloc for high-order pages */
        if (unlikely(pp_order))
                return __page_pool_alloc_page_order(pool, gfp);
 
-       if (unlikely(!alloc_pages_bulk_list(gfp, bulk, &page_list)))
+       /* Unnecessary as alloc cache is empty, but guarantees zero count */
+       if (unlikely(pool->alloc.count > 0))
+               return pool->alloc.cache[--pool->alloc.count];
+
+       /* Mark empty alloc.cache slots "empty" for alloc_pages_bulk_array */
+       memset(&pool->alloc.cache, 0, sizeof(void *) * bulk);
+
+       nr_pages = alloc_pages_bulk_array(gfp, bulk, pool->alloc.cache);
+       if (unlikely(!nr_pages))
                return NULL;
 
-       list_for_each_entry_safe(page, next, &page_list, lru) {
-               list_del(&page->lru);
+       /* Pages have been filled into alloc.cache array, but count is zero and
+        * page element have not been (possibly) DMA mapped.
+        */
+       for (i = 0; i < nr_pages; i++) {
+               page = pool->alloc.cache[i];
                if ((pp_flags & PP_FLAG_DMA_MAP) &&
                    unlikely(!page_pool_dma_map(pool, page))) {
                        put_page(page);
                        continue;
                }
-               /* Alloc cache have room as it is empty on function call */
                pool->alloc.cache[pool->alloc.count++] = page;
                /* Track how many pages are held 'in-flight' */
                pool->pages_state_hold_cnt++;