[PATCH AUTOSEL 5.7 26/53] i40e: protect ring accesses with READ- and WRITE_ONCE

Sasha Levin
2020-07-02T01:35:29Z

From: Ciara Loftus <ciara.loftus@intel.com>

[ Upstream commit d59e267912cd90b0adf33b4659050d831e746317 ]

READ_ONCE should be used when reading rings prior to accessing the
statistics pointer. Introduce this as well as the corresponding WRITE_ONCE
usage when allocating and freeing the rings, to ensure protected access.

Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/intel/i40e/i40e_main.c | 29 ++++++++++++++-------
1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 2a037ec244b94..80dc5fcb82db7 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -439,11 +439,15 @@ static void i40e_get_netdev_stats_struct(struct net_device *netdev,
i40e_get_netdev_stats_struct_tx(ring, stats);

if (i40e_enabled_xdp_vsi(vsi)) {
- ring++;
+ ring = READ_ONCE(vsi->xdp_rings[i]);
+ if (!ring)
+ continue;
i40e_get_netdev_stats_struct_tx(ring, stats);
}

- ring++;
+ ring = READ_ONCE(vsi->rx_rings[i]);
+ if (!ring)
+ continue;
do {
start = u64_stats_fetch_begin_irq(&ring->syncp);
packets = ring->stats.packets;
@@ -787,6 +791,8 @@ static void i40e_update_vsi_stats(struct i40e_vsi *vsi)
for (q = 0; q < vsi->num_queue_pairs; q++) {
/* locate Tx ring */
p = READ_ONCE(vsi->tx_rings[q]);
+ if (!p)
+ continue;

do {
start = u64_stats_fetch_begin_irq(&p->syncp);
@@ -800,8 +806,11 @@ static void i40e_update_vsi_stats(struct i40e_vsi *vsi)
tx_linearize += p->tx_stats.tx_linearize;
tx_force_wb += p->tx_stats.tx_force_wb;

- /* Rx queue is part of the same block as Tx queue */
- p = &p[1];
+ /* locate Rx ring */
+ p = READ_ONCE(vsi->rx_rings[q]);
+ if (!p)
+ continue;
+
do {
start = u64_stats_fetch_begin_irq(&p->syncp);
packets = p->stats.packets;
@@ -10816,10 +10825,10 @@ static void i40e_vsi_clear_rings(struct i40e_vsi *vsi)
if (vsi->tx_rings && vsi->tx_rings[0]) {
for (i = 0; i < vsi->alloc_queue_pairs; i++) {
kfree_rcu(vsi->tx_rings[i], rcu);
- vsi->tx_rings[i] = NULL;
- vsi->rx_rings[i] = NULL;
+ WRITE_ONCE(vsi->tx_rings[i], NULL);
+ WRITE_ONCE(vsi->rx_rings[i], NULL);
if (vsi->xdp_rings)
- vsi->xdp_rings[i] = NULL;
+ WRITE_ONCE(vsi->xdp_rings[i], NULL);
}
}
}
@@ -10853,7 +10862,7 @@ static int i40e_alloc_rings(struct i40e_vsi *vsi)
if (vsi->back->hw_features & I40E_HW_WB_ON_ITR_CAPABLE)
ring->flags = I40E_TXR_FLAGS_WB_ON_ITR;
ring->itr_setting = pf->tx_itr_default;
- vsi->tx_rings[i] = ring++;
+ WRITE_ONCE(vsi->tx_rings[i], ring++);

if (!i40e_enabled_xdp_vsi(vsi))
goto setup_rx;
@@ -10871,7 +10880,7 @@ static int i40e_alloc_rings(struct i40e_vsi *vsi)
ring->flags = I40E_TXR_FLAGS_WB_ON_ITR;
set_ring_xdp(ring);
ring->itr_setting = pf->tx_itr_default;
- vsi->xdp_rings[i] = ring++;
+ WRITE_ONCE(vsi->xdp_rings[i], ring++);

setup_rx:
ring->queue_index = i;
@@ -10884,7 +10893,7 @@ static int i40e_alloc_rings(struct i40e_vsi *vsi)
ring->size = 0;
ring->dcb_tc = 0;
ring->itr_setting = pf->rx_itr_default;
- vsi->rx_rings[i] = ring;
+ WRITE_ONCE(vsi->rx_rings[i], ring);
}

return 0;
--
2.25.1