1 files changed, 94 insertions, 9 deletions

diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index 694d055e01ef..2cbcdbdec254 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -16,14 +16,16 @@
  * page_pool_alloc_pages() call.  Drivers should likely use
  * page_pool_dev_alloc_pages() replacing dev_alloc_pages().
  *
- * If page_pool handles DMA mapping (use page->private), then API user
- * is responsible for invoking page_pool_put_page() once.  In-case of
- * elevated refcnt, the DMA state is released, assuming other users of
- * the page will eventually call put_page().
+ * API keeps track of in-flight pages, in-order to let API user know
+ * when it is safe to dealloactor page_pool object.  Thus, API users
+ * must make sure to call page_pool_release_page() when a page is
+ * "leaving" the page_pool.  Or call page_pool_put_page() where
+ * appropiate.  For maintaining correct accounting.
  *
- * If no DMA mapping is done, then it can act as shim-layer that
- * fall-through to alloc_page.  As no state is kept on the page, the
- * regular put_page() call is sufficient.
+ * API user must only call page_pool_put_page() once on a page, as it
+ * will either recycle the page, or in case of elevated refcnt, it
+ * will release the DMA mapping and in-flight state accounting.  We
+ * hope to lift this requirement in the future.
  */
 #ifndef _NET_PAGE_POOL_H
 #define _NET_PAGE_POOL_H
@@ -66,9 +68,10 @@ struct page_pool_params {
 };
 
 struct page_pool {
-	struct rcu_head rcu;
 	struct page_pool_params p;
 
+        u32 pages_state_hold_cnt;
+
 	/*
 	 * Data structure for allocation side
 	 *
@@ -96,6 +99,14 @@ struct page_pool {
 	 * TODO: Implement bulk return pages into this structure.
 	 */
 	struct ptr_ring ring;
+
+	atomic_t pages_state_release_cnt;
+
+	/* A page_pool is strictly tied to a single RX-queue being
+	 * protected by NAPI, due to above pp_alloc_cache. This
+	 * refcnt serves purpose is to simplify drivers error handling.
+	 */
+	refcount_t user_cnt;
 };
 
 struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
@@ -107,9 +118,36 @@ static inline struct page *page_pool_dev_alloc_pages(struct page_pool *pool)
 	return page_pool_alloc_pages(pool, gfp);
 }
 
+/* get the stored dma direction. A driver might decide to treat this locally and
+ * avoid the extra cache line from page_pool to determine the direction
+ */
+static
+inline enum dma_data_direction page_pool_get_dma_dir(struct page_pool *pool)
+{
+	return pool->p.dma_dir;
+}
+
 struct page_pool *page_pool_create(const struct page_pool_params *params);
 
-void page_pool_destroy(struct page_pool *pool);
+void __page_pool_free(struct page_pool *pool);
+static inline void page_pool_free(struct page_pool *pool)
+{
+	/* When page_pool isn't compiled-in, net/core/xdp.c doesn't
+	 * allow registering MEM_TYPE_PAGE_POOL, but shield linker.
+	 */
+#ifdef CONFIG_PAGE_POOL
+	__page_pool_free(pool);
+#endif
+}
+
+/* Drivers use this instead of page_pool_free */
+static inline void page_pool_destroy(struct page_pool *pool)
+{
+	if (!pool)
+		return;
+
+	page_pool_free(pool);
+}
 
 /* Never call this directly, use helpers below */
 void __page_pool_put_page(struct page_pool *pool,
@@ -132,6 +170,43 @@ static inline void page_pool_recycle_direct(struct page_pool *pool,
 	__page_pool_put_page(pool, page, true);
 }
 
+/* API user MUST have disconnected alloc-side (not allowed to call
+ * page_pool_alloc_pages()) before calling this.  The free-side can
+ * still run concurrently, to handle in-flight packet-pages.
+ *
+ * A request to shutdown can fail (with false) if there are still
+ * in-flight packet-pages.
+ */
+bool __page_pool_request_shutdown(struct page_pool *pool);
+static inline bool page_pool_request_shutdown(struct page_pool *pool)
+{
+	bool safe_to_remove = false;
+
+#ifdef CONFIG_PAGE_POOL
+	safe_to_remove = __page_pool_request_shutdown(pool);
+#endif
+	return safe_to_remove;
+}
+
+/* Disconnects a page (from a page_pool).  API users can have a need
+ * to disconnect a page (from a page_pool), to allow it to be used as
+ * a regular page (that will eventually be returned to the normal
+ * page-allocator via put_page).
+ */
+void page_pool_unmap_page(struct page_pool *pool, struct page *page);
+static inline void page_pool_release_page(struct page_pool *pool,
+					  struct page *page)
+{
+#ifdef CONFIG_PAGE_POOL
+	page_pool_unmap_page(pool, page);
+#endif
+}
+
+static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
+{
+	return page->dma_addr;
+}
+
 static inline bool is_page_pool_compiled_in(void)
 {
 #ifdef CONFIG_PAGE_POOL
@@ -141,4 +216,14 @@ static inline bool is_page_pool_compiled_in(void)
 #endif
 }
 
+static inline void page_pool_get(struct page_pool *pool)
+{
+	refcount_inc(&pool->user_cnt);
+}
+
+static inline bool page_pool_put(struct page_pool *pool)
+{
+	return refcount_dec_and_test(&pool->user_cnt);
+}
+
 #endif /* _NET_PAGE_POOL_H */