Merge branch '100GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/net-queue

Tony Nguyen says:

====================
Intel Wired LAN Driver Updates 2021-11-22

Maciej Fijalkowski says:

Here are the two fixes for issues around ethtool's set_channels()
callback for ice driver. Both are related to XDP resources. First one
corrects the size of vsi->txq_map that is used to track the usage of Tx
resources and the second one prevents the wrong refcounting of bpf_prog.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/ice/ice_lib.c

@@ -89,8 +89,13 @@ static int ice_vsi_alloc_arrays(struct ice_vsi *vsi)
 	if (!vsi->rx_rings)
 		goto err_rings;
 
-	/* XDP will have vsi->alloc_txq Tx queues as well, so double the size */
-	vsi->txq_map = devm_kcalloc(dev, (2 * vsi->alloc_txq),
+	/* txq_map needs to have enough space to track both Tx (stack) rings
+	 * and XDP rings; at this point vsi->num_xdp_txq might not be set,
+	 * so use num_possible_cpus() as we want to always provide XDP ring
+	 * per CPU, regardless of queue count settings from user that might
+	 * have come from ethtool's set_channels() callback;
+	 */
+	vsi->txq_map = devm_kcalloc(dev, (vsi->alloc_txq + num_possible_cpus()),
 				    sizeof(*vsi->txq_map), GFP_KERNEL);
 
 	if (!vsi->txq_map)

drivers/net/ethernet/intel/ice/ice_main.c

@@ -2609,7 +2609,18 @@ int ice_prepare_xdp_rings(struct ice_vsi *vsi, struct bpf_prog *prog)
 			ice_stat_str(status));
 		goto clear_xdp_rings;
 	}
-	ice_vsi_assign_bpf_prog(vsi, prog);
+
+	/* assign the prog only when it's not already present on VSI;
+	 * this flow is a subject of both ethtool -L and ndo_bpf flows;
+	 * VSI rebuild that happens under ethtool -L can expose us to
+	 * the bpf_prog refcount issues as we would be swapping same
+	 * bpf_prog pointers from vsi->xdp_prog and calling bpf_prog_put
+	 * on it as it would be treated as an 'old_prog'; for ndo_bpf
+	 * this is not harmful as dev_xdp_install bumps the refcount
+	 * before calling the op exposed by the driver;
+	 */
+	if (!ice_is_xdp_ena_vsi(vsi))
+		ice_vsi_assign_bpf_prog(vsi, prog);
 
 	return 0;
 clear_xdp_rings:
@@ -2785,6 +2796,11 @@ ice_xdp_setup_prog(struct ice_vsi *vsi, struct bpf_prog *prog,
 		if (xdp_ring_err)
 			NL_SET_ERR_MSG_MOD(extack, "Freeing XDP Tx resources failed");
 	} else {
+		/* safe to call even when prog == vsi->xdp_prog as
+		 * dev_xdp_install in net/core/dev.c incremented prog's
+		 * refcount so corresponding bpf_prog_put won't cause
+		 * underflow
+		 */
 		ice_vsi_assign_bpf_prog(vsi, prog);
 	}