[PATCH AUTOSEL 5.7 25/53] ixgbe: protect ring accesses with READ- and WRITE_ONCE

Sasha Levin
2020-07-02T01:35:31Z

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

[ Upstream commit f140ad9fe2ae16f385f8fe4dc9cf67bb4c51d794 ]

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/ixgbe/ixgbe_lib.c | 12 ++++++------
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 14 +++++++++++---
2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
index fd9f5d41b5942..2e35c5706cf10 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
@@ -921,7 +921,7 @@ static int ixgbe_alloc_q_vector(struct ixgbe_adapter *adapter,
ring->queue_index = txr_idx;

/* assign ring to adapter */
- adapter->tx_ring[txr_idx] = ring;
+ WRITE_ONCE(adapter->tx_ring[txr_idx], ring);

/* update count and index */
txr_count--;
@@ -948,7 +948,7 @@ static int ixgbe_alloc_q_vector(struct ixgbe_adapter *adapter,
set_ring_xdp(ring);

/* assign ring to adapter */
- adapter->xdp_ring[xdp_idx] = ring;
+ WRITE_ONCE(adapter->xdp_ring[xdp_idx], ring);

/* update count and index */
xdp_count--;
@@ -991,7 +991,7 @@ static int ixgbe_alloc_q_vector(struct ixgbe_adapter *adapter,
ring->queue_index = rxr_idx;

/* assign ring to adapter */
- adapter->rx_ring[rxr_idx] = ring;
+ WRITE_ONCE(adapter->rx_ring[rxr_idx], ring);

/* update count and index */
rxr_count--;
@@ -1020,13 +1020,13 @@ static void ixgbe_free_q_vector(struct ixgbe_adapter *adapter, int v_idx)

ixgbe_for_each_ring(ring, q_vector->tx) {
if (ring_is_xdp(ring))
- adapter->xdp_ring[ring->queue_index] = NULL;
+ WRITE_ONCE(adapter->xdp_ring[ring->queue_index], NULL);
else
- adapter->tx_ring[ring->queue_index] = NULL;
+ WRITE_ONCE(adapter->tx_ring[ring->queue_index], NULL);
}

ixgbe_for_each_ring(ring, q_vector->rx)
- adapter->rx_ring[ring->queue_index] = NULL;
+ WRITE_ONCE(adapter->rx_ring[ring->queue_index], NULL);

adapter->q_vector[v_idx] = NULL;
napi_hash_del(&q_vector->napi);
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index ea6834bae04c0..a32a072761aa2 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -7065,7 +7065,10 @@ void ixgbe_update_stats(struct ixgbe_adapter *adapter)
}

for (i = 0; i < adapter->num_rx_queues; i++) {
- struct ixgbe_ring *rx_ring = adapter->rx_ring[i];
+ struct ixgbe_ring *rx_ring = READ_ONCE(adapter->rx_ring[i]);
+
+ if (!rx_ring)
+ continue;
non_eop_descs += rx_ring->rx_stats.non_eop_descs;
alloc_rx_page += rx_ring->rx_stats.alloc_rx_page;
alloc_rx_page_failed += rx_ring->rx_stats.alloc_rx_page_failed;
@@ -7086,15 +7089,20 @@ void ixgbe_update_stats(struct ixgbe_adapter *adapter)
packets = 0;
/* gather some stats to the adapter struct that are per queue */
for (i = 0; i < adapter->num_tx_queues; i++) {
- struct ixgbe_ring *tx_ring = adapter->tx_ring[i];
+ struct ixgbe_ring *tx_ring = READ_ONCE(adapter->tx_ring[i]);
+
+ if (!tx_ring)
+ continue;
restart_queue += tx_ring->tx_stats.restart_queue;
tx_busy += tx_ring->tx_stats.tx_busy;
bytes += tx_ring->stats.bytes;
packets += tx_ring->stats.packets;
}
for (i = 0; i < adapter->num_xdp_queues; i++) {
- struct ixgbe_ring *xdp_ring = adapter->xdp_ring[i];
+ struct ixgbe_ring *xdp_ring = READ_ONCE(adapter->xdp_ring[i]);

+ if (!xdp_ring)
+ continue;
restart_queue += xdp_ring->tx_stats.restart_queue;
tx_busy += xdp_ring->tx_stats.tx_busy;
bytes += xdp_ring->stats.bytes;
--
2.25.1