release/5.2.35/net-i40e-Fix-concurrency-issues-between-config-flow-.patch

From a436b6a090299080c9974bf851e847d3c8c8c62a Mon Sep 17 00:00:00 2001
From: Maxim Mikityanskiy <maximmi@mellanox.com>
Date: Tue, 17 Dec 2019 16:20:45 +0000
Subject: [PATCH] net/i40e: Fix concurrency issues between config flow and XSK
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

commit b3873a5be757b44d51af542a50a6f2a3b6f95284 upstream.

Use synchronize_rcu to wait until the XSK wakeup function finishes
before destroying the resources it uses:

1. i40e_down already calls synchronize_rcu. On i40e_down either
__I40E_VSI_DOWN or __I40E_CONFIG_BUSY is set. Check the latter in
i40e_xsk_wakeup (the former is already checked there).

2. After switching the XDP program, call synchronize_rcu to let
i40e_xsk_wakeup exit before the XDP program is freed.

3. Changing the number of channels brings the interface down (see
i40e_prep_for_reset and i40e_pf_quiesce_all_vsi).

4. Disabling UMEM sets __I40E_CONFIG_BUSY, too.

Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191217162023.16011-4-maximmi@mellanox.com
[PG: note async_xmit ---> wakeup rename in mainline 9116e5e2b1ff.]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
index 7ce42040b851..9ef2d3f86aff 100644
--- a/drivers/net/ethernet/intel/i40e/i40e.h
+++ b/drivers/net/ethernet/intel/i40e/i40e.h
@@ -1125,7 +1125,7 @@ void i40e_set_fec_in_flags(u8 fec_cfg, u32 *flags);
 
 static inline bool i40e_enabled_xdp_vsi(struct i40e_vsi *vsi)
 {
-	return !!vsi->xdp_prog;
+	return !!READ_ONCE(vsi->xdp_prog);
 }
 
 int i40e_create_queue_channel(struct i40e_vsi *vsi, struct i40e_channel *ch);
diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index f86d66139ecc..6bfd0560a7e7 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -6789,8 +6789,8 @@ void i40e_down(struct i40e_vsi *vsi)
 	for (i = 0; i < vsi->num_queue_pairs; i++) {
 		i40e_clean_tx_ring(vsi->tx_rings[i]);
 		if (i40e_enabled_xdp_vsi(vsi)) {
-			/* Make sure that in-progress ndo_xdp_xmit
-			 * calls are completed.
+			/* Make sure that in-progress ndo_xdp_xmit and
+			 * ndo_xsk_wakeup calls are completed.
 			 */
 			synchronize_rcu();
 			i40e_clean_tx_ring(vsi->xdp_rings[i]);
@@ -12015,8 +12015,12 @@ static int i40e_xdp_setup(struct i40e_vsi *vsi,
 
 	old_prog = xchg(&vsi->xdp_prog, prog);
 
-	if (need_reset)
+	if (need_reset) {
+		if (!prog)
+			/* Wait until ndo_xsk_wakeup completes. */
+			synchronize_rcu();
 		i40e_reset_and_rebuild(pf, true, true);
+	}
 
 	for (i = 0; i < vsi->num_queue_pairs; i++)
 		WRITE_ONCE(vsi->rx_rings[i]->xdp_prog, vsi->xdp_prog);
diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
index 1b17486543ac..30e731272df4 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
@@ -772,8 +772,12 @@ int i40e_xsk_async_xmit(struct net_device *dev, u32 queue_id)
 {
 	struct i40e_netdev_priv *np = netdev_priv(dev);
 	struct i40e_vsi *vsi = np->vsi;
+	struct i40e_pf *pf = vsi->back;
 	struct i40e_ring *ring;
 
+	if (test_bit(__I40E_CONFIG_BUSY, pf->state))
+		return -ENETDOWN;
+
 	if (test_bit(__I40E_VSI_DOWN, vsi->state))
 		return -ENETDOWN;
 
-- 
2.7.4