i40e: fix XDP_REDIRECT/XDP xmit ring cleanup race
When the driver clears the XDP xmit ring due to re-configuration or
teardown, in-progress ndo_xdp_xmit must be taken into consideration.
The ndo_xdp_xmit function is typically called from a NAPI context that
the driver does not control. Therefore, we must be careful not to
clear the XDP ring, while the call is on-going. This patch adds a
synchronize_rcu() to wait for napi(s) (preempt-disable regions and
softirqs), prior clearing the queue. Further, the __I40E_CONFIG_BUSY
flag is checked in the ndo_xdp_xmit implementation to avoid touching
the XDP xmit queue during re-configuration.
Fixes: d9314c474d4f ("i40e: add support for XDP_REDIRECT")
Fixes: 123cecd427b6 ("i40e: added queue pair disable/enable functions")
Reported-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index a7e14e9..6c97667 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -3709,6 +3709,7 @@ int i40e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames,
struct i40e_netdev_priv *np = netdev_priv(dev);
unsigned int queue_index = smp_processor_id();
struct i40e_vsi *vsi = np->vsi;
+ struct i40e_pf *pf = vsi->back;
struct i40e_ring *xdp_ring;
int drops = 0;
int i;
@@ -3716,7 +3717,8 @@ int i40e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames,
if (test_bit(__I40E_VSI_DOWN, vsi->state))
return -ENETDOWN;
- if (!i40e_enabled_xdp_vsi(vsi) || queue_index >= vsi->num_queue_pairs)
+ if (!i40e_enabled_xdp_vsi(vsi) || queue_index >= vsi->num_queue_pairs ||
+ test_bit(__I40E_CONFIG_BUSY, pf->state))
return -ENXIO;
if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))