[PATCH net-next 01/12] page_pool: allow mixing PPs within one bulk

[Alexander Lobakin <aleksander.lobakin@intel.com>]

The main reason for this change was to allow mixing pages from different
&page_pools within one &xdp_buff/&xdp_frame. Why not? With stuff like
devmem and io_uring zerocopy Rx, it's required to have separate PPs for
header buffers and payload buffers.
Adjust xdp_return_frame_bulk() and page_pool_put_netmem_bulk(), so that
they won't be tied to a particular pool. Let the latter create a
separate bulk of pages which's PP is different from the first netmem of
the bulk and process it after the main loop.
This greatly optimizes xdp_return_frame_bulk(): no more hashtable
lookups and forced flushes on PP mismatch. Also make
xdp_flush_frame_bulk() inline, as it's just one if + function call + one
u32 read, not worth extending the call ladder.

Co-developed-by: Toke Høiland-Jørgensen <toke@redhat.com> # iterative
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Suggested-by: Jakub Kicinski <kuba@kernel.org> # while (count)
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
---
 include/net/page_pool/types.h |   6 +-
 include/net/xdp.h             |  16 +++--
 net/core/page_pool.c          | 109 ++++++++++++++++++++++------------
 net/core/xdp.c                |  29 +--------
 4 files changed, 87 insertions(+), 73 deletions(-)

diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
index 1ea16b0e9c79..05a864031271 100644
--- a/include/net/page_pool/types.h
+++ b/include/net/page_pool/types.h
@@ -259,8 +259,7 @@ void page_pool_disable_direct_recycling(struct page_pool *pool);
 void page_pool_destroy(struct page_pool *pool);
 void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *),
 			   const struct xdp_mem_info *mem);
-void page_pool_put_netmem_bulk(struct page_pool *pool, netmem_ref *data,
-			       u32 count);
+void page_pool_put_netmem_bulk(netmem_ref *data, u32 count);
 #else
 static inline void page_pool_destroy(struct page_pool *pool)
 {
@@ -272,8 +271,7 @@ static inline void page_pool_use_xdp_mem(struct page_pool *pool,
 {
 }
 
-static inline void page_pool_put_netmem_bulk(struct page_pool *pool,
-					     netmem_ref *data, u32 count)
+static inline void page_pool_put_netmem_bulk(netmem_ref *data, u32 count)
 {
 }
 #endif
diff --git a/include/net/xdp.h b/include/net/xdp.h
index f4020b29122f..9e7eb8223513 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -11,6 +11,8 @@
 #include <linux/netdevice.h>
 #include <linux/skbuff.h> /* skb_shared_info */
 
+#include <net/page_pool/types.h>
+
 /**
  * DOC: XDP RX-queue information
  *
@@ -193,14 +195,12 @@ xdp_frame_is_frag_pfmemalloc(const struct xdp_frame *frame)
 #define XDP_BULK_QUEUE_SIZE	16
 struct xdp_frame_bulk {
 	int count;
-	void *xa;
 	netmem_ref q[XDP_BULK_QUEUE_SIZE];
 };
 
 static __always_inline void xdp_frame_bulk_init(struct xdp_frame_bulk *bq)
 {
-	/* bq->count will be zero'ed when bq->xa gets updated */
-	bq->xa = NULL;
+	bq->count = 0;
 }
 
 static inline struct skb_shared_info *
@@ -317,10 +317,18 @@ void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct,
 void xdp_return_frame(struct xdp_frame *xdpf);
 void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
 void xdp_return_buff(struct xdp_buff *xdp);
-void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq);
 void xdp_return_frame_bulk(struct xdp_frame *xdpf,
 			   struct xdp_frame_bulk *bq);
 
+static inline void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq)
+{
+	if (unlikely(!bq->count))
+		return;
+
+	page_pool_put_netmem_bulk(bq->q, bq->count);
+	bq->count = 0;
+}
+
 static __always_inline unsigned int
 xdp_get_frame_len(const struct xdp_frame *xdpf)
 {
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 4c85b77cfdac..10cef95f12e3 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -839,9 +839,41 @@ void page_pool_put_unrefed_page(struct page_pool *pool, struct page *page,
 }
 EXPORT_SYMBOL(page_pool_put_unrefed_page);
 
+static void page_pool_recycle_ring_bulk(struct page_pool *pool,
+					netmem_ref *bulk,
+					u32 bulk_len)
+{
+	bool in_softirq;
+	u32 i;
+
+	/* Bulk produce into ptr_ring page_pool cache */
+	in_softirq = page_pool_producer_lock(pool);
+
+	for (i = 0; i < bulk_len; i++) {
+		if (__ptr_ring_produce(&pool->ring, (__force void *)bulk[i])) {
+			/* ring full */
+			recycle_stat_inc(pool, ring_full);
+			break;
+		}
+	}
+
+	page_pool_producer_unlock(pool, in_softirq);
+	recycle_stat_add(pool, ring, i);
+
+	/* Hopefully all pages were returned into ptr_ring */
+	if (likely(i == bulk_len))
+		return;
+
+	/*
+	 * ptr_ring cache is full, free remaining pages outside producer lock
+	 * since put_page() with refcnt == 1 can be an expensive operation.
+	 */
+	for (; i < bulk_len; i++)
+		page_pool_return_page(pool, bulk[i]);
+}
+
 /**
  * page_pool_put_netmem_bulk() - release references on multiple netmems
- * @pool:	pool from which pages were allocated
  * @data:	array holding netmem references
  * @count:	number of entries in @data
  *
@@ -854,52 +886,55 @@ EXPORT_SYMBOL(page_pool_put_unrefed_page);
  * Please note the caller must not use data area after running
  * page_pool_put_netmem_bulk(), as this function overwrites it.
  */
-void page_pool_put_netmem_bulk(struct page_pool *pool, netmem_ref *data,
-			       u32 count)
+void page_pool_put_netmem_bulk(netmem_ref *data, u32 count)
 {
-	int i, bulk_len = 0;
-	bool allow_direct;
-	bool in_softirq;
-
-	allow_direct = page_pool_napi_local(pool);
+	u32 bulk_len = 0;
 
-	for (i = 0; i < count; i++) {
+	for (u32 i = 0; i < count; i++) {
 		netmem_ref netmem = netmem_compound_head(data[i]);
 
-		/* It is not the last user for the page frag case */
-		if (!page_pool_is_last_ref(netmem))
-			continue;
-
-		netmem = __page_pool_put_page(pool, netmem, -1, allow_direct);
-		/* Approved for bulk recycling in ptr_ring cache */
-		if (netmem)
+		if (page_pool_is_last_ref(netmem))
 			data[bulk_len++] = netmem;
 	}
 
-	if (!bulk_len)
-		return;
-
-	/* Bulk producer into ptr_ring page_pool cache */
-	in_softirq = page_pool_producer_lock(pool);
-	for (i = 0; i < bulk_len; i++) {
-		if (__ptr_ring_produce(&pool->ring, (__force void *)data[i])) {
-			/* ring full */
-			recycle_stat_inc(pool, ring_full);
-			break;
+	count = bulk_len;
+	while (count) {
+		netmem_ref bulk[XDP_BULK_QUEUE_SIZE];
+		struct page_pool *pool = NULL;
+		bool allow_direct;
+		u32 foreign = 0;
+
+		bulk_len = 0;
+
+		for (u32 i = 0; i < count; i++) {
+			struct page_pool *netmem_pp;
+			netmem_ref netmem = data[i];
+
+			netmem_pp = netmem_get_pp(netmem);
+			if (unlikely(!pool)) {
+				pool = netmem_pp;
+				allow_direct = page_pool_napi_local(pool);
+			} else if (netmem_pp != pool) {
+				/*
+				 * If the netmem belongs to a different
+				 * page_pool, save it for another round.
+				 */
+				data[foreign++] = netmem;
+				continue;
+			}
+
+			netmem = __page_pool_put_page(pool, netmem, -1,
+						      allow_direct);
+			/* Approved for bulk recycling in ptr_ring cache */
+			if (netmem)
+				bulk[bulk_len++] = netmem;
 		}
-	}
-	recycle_stat_add(pool, ring, i);
-	page_pool_producer_unlock(pool, in_softirq);
 
-	/* Hopefully all pages was return into ptr_ring */
-	if (likely(i == bulk_len))
-		return;
+		if (bulk_len)
+			page_pool_recycle_ring_bulk(pool, bulk, bulk_len);
 
-	/* ptr_ring cache full, free remaining pages outside producer lock
-	 * since put_page() with refcnt == 1 can be an expensive operation
-	 */
-	for (; i < bulk_len; i++)
-		page_pool_return_page(pool, data[i]);
+		count = foreign;
+	}
 }
 EXPORT_SYMBOL(page_pool_put_netmem_bulk);
 
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 938ad15c9857..56127e8ec85f 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -511,46 +511,19 @@ EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
  * xdp_frame_bulk is usually stored/allocated on the function
  * call-stack to avoid locking penalties.
  */
-void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq)
-{
-	struct xdp_mem_allocator *xa = bq->xa;
-
-	if (unlikely(!xa || !bq->count))
-		return;
-
-	page_pool_put_netmem_bulk(xa->page_pool, bq->q, bq->count);
-	/* bq->xa is not cleared to save lookup, if mem.id same in next bulk */
-	bq->count = 0;
-}
-EXPORT_SYMBOL_GPL(xdp_flush_frame_bulk);
 
 /* Must be called with rcu_read_lock held */
 void xdp_return_frame_bulk(struct xdp_frame *xdpf,
 			   struct xdp_frame_bulk *bq)
 {
-	struct xdp_mem_info *mem = &xdpf->mem;
-	struct xdp_mem_allocator *xa;
-
-	if (mem->type != MEM_TYPE_PAGE_POOL) {
+	if (xdpf->mem.type != MEM_TYPE_PAGE_POOL) {
 		xdp_return_frame(xdpf);
 		return;
 	}
 
-	xa = bq->xa;
-	if (unlikely(!xa)) {
-		xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
-		bq->count = 0;
-		bq->xa = xa;
-	}
-
 	if (bq->count == XDP_BULK_QUEUE_SIZE)
 		xdp_flush_frame_bulk(bq);
 
-	if (unlikely(mem->id != xa->mem.id)) {
-		xdp_flush_frame_bulk(bq);
-		bq->xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
-	}
-
 	if (unlikely(xdp_frame_has_frags(xdpf))) {
 		struct skb_shared_info *sinfo;
 		int i;
-- 
2.47.1