1 files changed, 103 insertions, 30 deletions

diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index 79a805542d0f..ea5fb70e5101 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -84,6 +84,48 @@ struct page_pool_params {
 	void *init_arg;
 };
 
+#ifdef CONFIG_PAGE_POOL_STATS
+struct page_pool_alloc_stats {
+	u64 fast; /* fast path allocations */
+	u64 slow; /* slow-path order 0 allocations */
+	u64 slow_high_order; /* slow-path high order allocations */
+	u64 empty; /* failed refills due to empty ptr ring, forcing
+		    * slow path allocation
+		    */
+	u64 refill; /* allocations via successful refill */
+	u64 waive;  /* failed refills due to numa zone mismatch */
+};
+
+struct page_pool_recycle_stats {
+	u64 cached;	/* recycling placed page in the cache. */
+	u64 cache_full; /* cache was full */
+	u64 ring;	/* recycling placed page back into ptr ring */
+	u64 ring_full;	/* page was released from page-pool because
+			 * PTR ring was full.
+			 */
+	u64 released_refcnt; /* page released because of elevated
+			      * refcnt
+			      */
+};
+
+/* This struct wraps the above stats structs so users of the
+ * page_pool_get_stats API can pass a single argument when requesting the
+ * stats for the page pool.
+ */
+struct page_pool_stats {
+	struct page_pool_alloc_stats alloc_stats;
+	struct page_pool_recycle_stats recycle_stats;
+};
+
+/*
+ * Drivers that wish to harvest page pool stats and report them to users
+ * (perhaps via ethtool, debugfs, or another mechanism) can allocate a
+ * struct page_pool_stats call page_pool_get_stats to get stats for the specified pool.
+ */
+bool page_pool_get_stats(struct page_pool *pool,
+			 struct page_pool_stats *stats);
+#endif
+
 struct page_pool {
 	struct page_pool_params p;
 
@@ -96,6 +138,11 @@ struct page_pool {
 	unsigned int frag_offset;
 	struct page *frag_page;
 	long frag_users;
+
+#ifdef CONFIG_PAGE_POOL_STATS
+	/* these stats are incremented while in softirq context */
+	struct page_pool_alloc_stats alloc_stats;
+#endif
 	u32 xdp_mem_id;
 
 	/*
@@ -126,6 +173,10 @@ struct page_pool {
 	 */
 	struct ptr_ring ring;
 
+#ifdef CONFIG_PAGE_POOL_STATS
+	/* recycle stats are per-cpu to avoid locking */
+	struct page_pool_recycle_stats __percpu *recycle_stats;
+#endif
 	atomic_t pages_state_release_cnt;
 
 	/* A page_pool is strictly tied to a single RX-queue being
@@ -201,21 +252,67 @@ static inline void page_pool_put_page_bulk(struct page_pool *pool, void **data,
 }
 #endif
 
-void page_pool_put_page(struct page_pool *pool, struct page *page,
-			unsigned int dma_sync_size, bool allow_direct);
+void page_pool_put_defragged_page(struct page_pool *pool, struct page *page,
+				  unsigned int dma_sync_size,
+				  bool allow_direct);
 
-/* Same as above but will try to sync the entire area pool->max_len */
-static inline void page_pool_put_full_page(struct page_pool *pool,
-					   struct page *page, bool allow_direct)
+static inline void page_pool_fragment_page(struct page *page, long nr)
+{
+	atomic_long_set(&page->pp_frag_count, nr);
+}
+
+static inline long page_pool_defrag_page(struct page *page, long nr)
+{
+	long ret;
+
+	/* If nr == pp_frag_count then we have cleared all remaining
+	 * references to the page. No need to actually overwrite it, instead
+	 * we can leave this to be overwritten by the calling function.
+	 *
+	 * The main advantage to doing this is that an atomic_read is
+	 * generally a much cheaper operation than an atomic update,
+	 * especially when dealing with a page that may be partitioned
+	 * into only 2 or 3 pieces.
+	 */
+	if (atomic_long_read(&page->pp_frag_count) == nr)
+		return 0;
+
+	ret = atomic_long_sub_return(nr, &page->pp_frag_count);
+	WARN_ON(ret < 0);
+	return ret;
+}
+
+static inline bool page_pool_is_last_frag(struct page_pool *pool,
+					  struct page *page)
+{
+	/* If fragments aren't enabled or count is 0 we were the last user */
+	return !(pool->p.flags & PP_FLAG_PAGE_FRAG) ||
+	       (page_pool_defrag_page(page, 1) == 0);
+}
+
+static inline void page_pool_put_page(struct page_pool *pool,
+				      struct page *page,
+				      unsigned int dma_sync_size,
+				      bool allow_direct)
 {
 	/* 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_put_page(pool, page, -1, allow_direct);
+	if (!page_pool_is_last_frag(pool, page))
+		return;
+
+	page_pool_put_defragged_page(pool, page, dma_sync_size, allow_direct);
 #endif
 }
 
+/* Same as above but will try to sync the entire area pool->max_len */
+static inline void page_pool_put_full_page(struct page_pool *pool,
+					   struct page *page, bool allow_direct)
+{
+	page_pool_put_page(pool, page, -1, allow_direct);
+}
+
 /* Same as above but the caller must guarantee safe context. e.g NAPI */
 static inline void page_pool_recycle_direct(struct page_pool *pool,
 					    struct page *page)
@@ -243,30 +340,6 @@ static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr)
 		page->dma_addr_upper = upper_32_bits(addr);
 }
 
-static inline void page_pool_set_frag_count(struct page *page, long nr)
-{
-	atomic_long_set(&page->pp_frag_count, nr);
-}
-
-static inline long page_pool_atomic_sub_frag_count_return(struct page *page,
-							  long nr)
-{
-	long ret;
-
-	/* As suggested by Alexander, atomic_long_read() may cover up the
-	 * reference count errors, so avoid calling atomic_long_read() in
-	 * the cases of freeing or draining the page_frags, where we would
-	 * not expect it to match or that are slowpath anyway.
-	 */
-	if (__builtin_constant_p(nr) &&
-	    atomic_long_read(&page->pp_frag_count) == nr)
-		return 0;
-
-	ret = atomic_long_sub_return(nr, &page->pp_frag_count);
-	WARN_ON(ret < 0);
-	return ret;
-}
-
 static inline bool is_page_pool_compiled_in(void)
 {
 #ifdef CONFIG_PAGE_POOL