bpf: Convert bpf_prog refcnt to atomic64_t

Similarly to bpf_map's refcnt/usercnt, convert bpf_prog's refcnt to atomic64
and remove artificial 32k limit. This allows to make bpf_prog's refcounting
non-failing, simplifying logic of users of bpf_prog_add/bpf_prog_inc.

Validated compilation by running allyesconfig kernel build.

Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191117172806.2195367-3-andriin@fb.com

6 files changed, 19 insertions, 56 deletions

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index c07172429c70..9da4fbee3cf7 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -3171,13 +3171,8 @@ static int bnxt_init_one_rx_ring(struct bnxt *bp, int ring_nr)
 	bnxt_init_rxbd_pages(ring, type);
 
 	if (BNXT_RX_PAGE_MODE(bp) && bp->xdp_prog) {
-		rxr->xdp_prog = bpf_prog_add(bp->xdp_prog, 1);
-		if (IS_ERR(rxr->xdp_prog)) {
-			int rc = PTR_ERR(rxr->xdp_prog);
-
-			rxr->xdp_prog = NULL;
-			return rc;
-		}
+		bpf_prog_add(bp->xdp_prog, 1);
+		rxr->xdp_prog = bp->xdp_prog;
 	}
 	prod = rxr->rx_prod;
 	for (i = 0; i < bp->rx_ring_size; i++) {
diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_main.c b/drivers/net/ethernet/cavium/thunder/nicvf_main.c
index 40a44dcb3d9b..f28409279ea4 100644
--- a/drivers/net/ethernet/cavium/thunder/nicvf_main.c
+++ b/drivers/net/ethernet/cavium/thunder/nicvf_main.c
@@ -1876,13 +1876,8 @@ static int nicvf_xdp_setup(struct nicvf *nic, struct bpf_prog *prog)
 
 	if (nic->xdp_prog) {
 		/* Attach BPF program */
-		nic->xdp_prog = bpf_prog_add(nic->xdp_prog, nic->rx_queues - 1);
-		if (!IS_ERR(nic->xdp_prog)) {
-			bpf_attached = true;
-		} else {
-			ret = PTR_ERR(nic->xdp_prog);
-			nic->xdp_prog = NULL;
-		}
+		bpf_prog_add(nic->xdp_prog, nic->rx_queues - 1);
+		bpf_attached = true;
 	}
 
 	/* Calculate Tx queues needed for XDP and network stack */
diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
index c26c0a7cbb6b..acc56606d3a5 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
@@ -1807,11 +1807,8 @@ static int setup_xdp(struct net_device *dev, struct bpf_prog *prog)
 	if (prog && !xdp_mtu_valid(priv, dev->mtu))
 		return -EINVAL;
 
-	if (prog) {
-		prog = bpf_prog_add(prog, priv->num_channels);
-		if (IS_ERR(prog))
-			return PTR_ERR(prog);
-	}
+	if (prog)
+		bpf_prog_add(prog, priv->num_channels);
 
 	up = netif_running(dev);
 	need_update = (!!priv->xdp_prog != !!prog);
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
index 40ec5acf79c0..d4697beeacc2 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
@@ -2286,11 +2286,7 @@ int mlx4_en_try_alloc_resources(struct mlx4_en_priv *priv,
 		lockdep_is_held(&priv->mdev->state_lock));
 
 	if (xdp_prog && carry_xdp_prog) {
-		xdp_prog = bpf_prog_add(xdp_prog, tmp->rx_ring_num);
-		if (IS_ERR(xdp_prog)) {
-			mlx4_en_free_resources(tmp);
-			return PTR_ERR(xdp_prog);
-		}
+		bpf_prog_add(xdp_prog, tmp->rx_ring_num);
 		for (i = 0; i < tmp->rx_ring_num; i++)
 			rcu_assign_pointer(tmp->rx_ring[i]->xdp_prog,
 					   xdp_prog);
@@ -2782,11 +2778,9 @@ static int mlx4_xdp_set(struct net_device *dev, struct bpf_prog *prog)
 	 * program for a new one.
 	 */
 	if (priv->tx_ring_num[TX_XDP] == xdp_ring_num) {
-		if (prog) {
-			prog = bpf_prog_add(prog, priv->rx_ring_num - 1);
-			if (IS_ERR(prog))
-				return PTR_ERR(prog);
-		}
+		if (prog)
+			bpf_prog_add(prog, priv->rx_ring_num - 1);
+
 		mutex_lock(&mdev->state_lock);
 		for (i = 0; i < priv->rx_ring_num; i++) {
 			old_prog = rcu_dereference_protected(
@@ -2807,13 +2801,8 @@ static int mlx4_xdp_set(struct net_device *dev, struct bpf_prog *prog)
 	if (!tmp)
 		return -ENOMEM;
 
-	if (prog) {
-		prog = bpf_prog_add(prog, priv->rx_ring_num - 1);
-		if (IS_ERR(prog)) {
-			err = PTR_ERR(prog);
-			goto out;
-		}
-	}
+	if (prog)
+		bpf_prog_add(prog, priv->rx_ring_num - 1);
 
 	mutex_lock(&mdev->state_lock);
 	memcpy(&new_prof, priv->prof, sizeof(struct mlx4_en_port_profile));
@@ -2862,7 +2851,6 @@ static int mlx4_xdp_set(struct net_device *dev, struct bpf_prog *prog)
 
 unlock_out:
 	mutex_unlock(&mdev->state_lock);
-out:
 	kfree(tmp);
 	return err;
 }
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 772bfdbdeb9c..1d4a66fb466a 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -408,12 +408,9 @@ static int mlx5e_alloc_rq(struct mlx5e_channel *c,
 		rq->stats = &c->priv->channel_stats[c->ix].rq;
 	INIT_WORK(&rq->recover_work, mlx5e_rq_err_cqe_work);
 
-	rq->xdp_prog = params->xdp_prog ? bpf_prog_inc(params->xdp_prog) : NULL;
-	if (IS_ERR(rq->xdp_prog)) {
-		err = PTR_ERR(rq->xdp_prog);
-		rq->xdp_prog = NULL;
-		goto err_rq_wq_destroy;
-	}
+	if (params->xdp_prog)
+		bpf_prog_inc(params->xdp_prog);
+	rq->xdp_prog = params->xdp_prog;
 
 	rq_xdp_ix = rq->ix;
 	if (xsk)
@@ -4406,16 +4403,11 @@ static int mlx5e_xdp_set(struct net_device *netdev, struct bpf_prog *prog)
 	/* no need for full reset when exchanging programs */
 	reset = (!priv->channels.params.xdp_prog || !prog);
 
-	if (was_opened && !reset) {
+	if (was_opened && !reset)
 		/* num_channels is invariant here, so we can take the
 		 * batched reference right upfront.
 		 */
-		prog = bpf_prog_add(prog, priv->channels.num);
-		if (IS_ERR(prog)) {
-			err = PTR_ERR(prog);
-			goto unlock;
-		}
-	}
+		bpf_prog_add(prog, priv->channels.num);
 
 	if (was_opened && reset) {
 		struct mlx5e_channels new_channels = {};
diff --git a/drivers/net/ethernet/qlogic/qede/qede_main.c b/drivers/net/ethernet/qlogic/qede/qede_main.c
index 8d1c208f778f..1e26964fe4e9 100644
--- a/drivers/net/ethernet/qlogic/qede/qede_main.c
+++ b/drivers/net/ethernet/qlogic/qede/qede_main.c
@@ -2107,12 +2107,8 @@ static int qede_start_queues(struct qede_dev *edev, bool clear_stats)
 			if (rc)
 				goto out;
 
-			fp->rxq->xdp_prog = bpf_prog_add(edev->xdp_prog, 1);
-			if (IS_ERR(fp->rxq->xdp_prog)) {
-				rc = PTR_ERR(fp->rxq->xdp_prog);
-				fp->rxq->xdp_prog = NULL;
-				goto out;
-			}
+			bpf_prog_add(edev->xdp_prog, 1);
+			fp->rxq->xdp_prog = edev->xdp_prog;
 		}
 
 		if (fp->type & QEDE_FASTPATH_TX) {