xsk: Create and free buffer pool independently from umem

Create and free the buffer pool independently from the umem. Move
these operations that are performed on the buffer pool from the
umem create and destroy functions to new create and destroy
functions just for the buffer pool. This so that in later commits
we can instantiate multiple buffer pools per umem when sharing a
umem between HW queues and/or devices. We also erradicate the
back pointer from the umem to the buffer pool as this will not
work when we introduce the possibility to have multiple buffer
pools per umem.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Link: https://lore.kernel.org/bpf/1598603189-32145-4-git-send-email-magnus.karlsson@intel.com

1 files changed, 64 insertions, 10 deletions

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index befc9a4331e1..5739f1951d7a 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -105,6 +105,46 @@ bool xsk_uses_need_wakeup(struct xsk_buff_pool *pool)
 }
 EXPORT_SYMBOL(xsk_uses_need_wakeup);
 
+struct xsk_buff_pool *xsk_get_pool_from_qid(struct net_device *dev,
+					    u16 queue_id)
+{
+	if (queue_id < dev->real_num_rx_queues)
+		return dev->_rx[queue_id].pool;
+	if (queue_id < dev->real_num_tx_queues)
+		return dev->_tx[queue_id].pool;
+
+	return NULL;
+}
+EXPORT_SYMBOL(xsk_get_pool_from_qid);
+
+void xsk_clear_pool_at_qid(struct net_device *dev, u16 queue_id)
+{
+	if (queue_id < dev->real_num_rx_queues)
+		dev->_rx[queue_id].pool = NULL;
+	if (queue_id < dev->real_num_tx_queues)
+		dev->_tx[queue_id].pool = NULL;
+}
+
+/* The buffer pool is stored both in the _rx struct and the _tx struct as we do
+ * not know if the device has more tx queues than rx, or the opposite.
+ * This might also change during run time.
+ */
+int xsk_reg_pool_at_qid(struct net_device *dev, struct xsk_buff_pool *pool,
+			u16 queue_id)
+{
+	if (queue_id >= max_t(unsigned int,
+			      dev->real_num_rx_queues,
+			      dev->real_num_tx_queues))
+		return -EINVAL;
+
+	if (queue_id < dev->real_num_rx_queues)
+		dev->_rx[queue_id].pool = pool;
+	if (queue_id < dev->real_num_tx_queues)
+		dev->_tx[queue_id].pool = pool;
+
+	return 0;
+}
+
 void xp_release(struct xdp_buff_xsk *xskb)
 {
 	xskb->pool->free_heads[xskb->pool->free_heads_cnt++] = xskb;
@@ -281,7 +321,7 @@ bool xsk_tx_peek_desc(struct xsk_buff_pool *pool, struct xdp_desc *desc)
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(xs, &umem->xsk_tx_list, list) {
-		if (!xskq_cons_peek_desc(xs->tx, desc, umem)) {
+		if (!xskq_cons_peek_desc(xs->tx, desc, pool)) {
 			xs->tx->queue_empty_descs++;
 			continue;
 		}
@@ -349,7 +389,7 @@ static int xsk_generic_xmit(struct sock *sk)
 	if (xs->queue_id >= xs->dev->real_num_tx_queues)
 		goto out;
 
-	while (xskq_cons_peek_desc(xs->tx, &desc, xs->umem)) {
+	while (xskq_cons_peek_desc(xs->tx, &desc, xs->pool)) {
 		char *buffer;
 		u64 addr;
 		u32 len;
@@ -667,6 +707,9 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
 			goto out_unlock;
 		}
 
+		/* Share the buffer pool with the other socket. */
+		xp_get_pool(umem_xs->pool);
+		xs->pool = umem_xs->pool;
 		xdp_get_umem(umem_xs->umem);
 		WRITE_ONCE(xs->umem, umem_xs->umem);
 		sockfd_put(sock);
@@ -675,9 +718,21 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
 		goto out_unlock;
 	} else {
 		/* This xsk has its own umem. */
-		err = xdp_umem_assign_dev(xs->umem, dev, qid, flags);
-		if (err)
+		xdp_umem_assign_dev(xs->umem, dev, qid);
+		xs->pool = xp_create_and_assign_umem(xs, xs->umem);
+		if (!xs->pool) {
+			err = -ENOMEM;
+			xdp_umem_clear_dev(xs->umem);
 			goto out_unlock;
+		}
+
+		err = xp_assign_dev(xs->pool, dev, qid, flags);
+		if (err) {
+			xp_destroy(xs->pool);
+			xs->pool = NULL;
+			xdp_umem_clear_dev(xs->umem);
+			goto out_unlock;
+		}
 	}
 
 	xs->dev = dev;
@@ -769,8 +824,6 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname,
 			return PTR_ERR(umem);
 		}
 
-		xs->pool = umem->pool;
-
 		/* Make sure umem is ready before it can be seen by others */
 		smp_wmb();
 		WRITE_ONCE(xs->umem, umem);
@@ -800,7 +853,7 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname,
 			&xs->umem->cq;
 		err = xsk_init_queue(entries, q, true);
 		if (optname == XDP_UMEM_FILL_RING)
-			xp_set_fq(xs->umem->pool, *q);
+			xp_set_fq(xs->pool, *q);
 		mutex_unlock(&xs->mutex);
 		return err;
 	}
@@ -1028,7 +1081,8 @@ static int xsk_notifier(struct notifier_block *this,
 
 				xsk_unbind_dev(xs);
 
-				/* Clear device references in umem. */
+				/* Clear device references. */
+				xp_clear_dev(xs->pool);
 				xdp_umem_clear_dev(xs->umem);
 			}
 			mutex_unlock(&xs->mutex);
@@ -1073,7 +1127,7 @@ static void xsk_destruct(struct sock *sk)
 	if (!sock_flag(sk, SOCK_DEAD))
 		return;
 
-	xdp_put_umem(xs->umem);
+	xp_put_pool(xs->pool);
 
 	sk_refcnt_debug_dec(sk);
 }
@@ -1081,8 +1135,8 @@ static void xsk_destruct(struct sock *sk)
 static int xsk_create(struct net *net, struct socket *sock, int protocol,
 		      int kern)
 {
-	struct sock *sk;
 	struct xdp_sock *xs;
+	struct sock *sk;
 
 	if (!ns_capable(net->user_ns, CAP_NET_RAW))
 		return -EPERM;