[PATCH v2] failsafe: fix segfault on hotplug event

[Luc Pelletier <lucp.at.work@gmail.com>]

When the failsafe PMD encounters a hotplug event, it switches its rx/tx
functions to "safe" ones that validate the sub-device's rx/tx functions
before calling them. It switches the rx/tx functions by changing the
function pointers in the rte_eth_dev structure.

Following commit 7a0935239b9e, the rx/tx functions of PMDs are no longer
called through the function pointers in the rte_eth_dev structure. They
are rather called through a flat array named rte_eth_fp_ops. The
function pointers in that array are initialized when the devices start
and are initialized.

When a hotplug event occurs, the function pointers in rte_eth_fp_ops
still point to the "unsafe" rx/tx functions in the failsafe PMD since
they haven't been updated. This results in a segmentation fault because
it ends up using the "unsafe" functions, when the "safe" functions
should have been used.

To fix the problem, the failsafe PMD code was changed to update the
function pointers in the rte_eth_fp_ops array when a hotplug event
occurs.

Fixes: 7a0935239b9e ("ethdev: make fast-path functions to use new flat array")
Cc: Konstantin Ananyev <konstantin.ananyev@intel.com>
Cc: stable@dpdk.org

Signed-off-by: Luc Pelletier <lucp.at.work@gmail.com>
---

v2:
* fixed git commit hashes in commit message

 drivers/net/failsafe/failsafe_rxtx.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/net/failsafe/failsafe_rxtx.c b/drivers/net/failsafe/failsafe_rxtx.c
index fe67293299..34d59dfbb1 100644
--- a/drivers/net/failsafe/failsafe_rxtx.c
+++ b/drivers/net/failsafe/failsafe_rxtx.c
@@ -5,6 +5,7 @@
 
 #include <rte_atomic.h>
 #include <rte_debug.h>
+#include <rte_ethdev.h>
 #include <rte_mbuf.h>
 #include <ethdev_driver.h>
 
@@ -44,9 +45,13 @@ failsafe_set_burst_fn(struct rte_eth_dev *dev, int force_safe)
 		DEBUG("Using safe RX bursts%s",
 		      (force_safe ? " (forced)" : ""));
 		dev->rx_pkt_burst = &failsafe_rx_burst;
+		rte_eth_fp_ops[dev->data->port_id].rx_pkt_burst =
+			&failsafe_rx_burst;
 	} else if (!need_safe && safe_set) {
 		DEBUG("Using fast RX bursts");
 		dev->rx_pkt_burst = &failsafe_rx_burst_fast;
+		rte_eth_fp_ops[dev->data->port_id].rx_pkt_burst =
+			&failsafe_rx_burst_fast;
 	}
 	need_safe = force_safe || fs_tx_unsafe(TX_SUBDEV(dev));
 	safe_set = (dev->tx_pkt_burst == &failsafe_tx_burst);
@@ -54,9 +59,13 @@ failsafe_set_burst_fn(struct rte_eth_dev *dev, int force_safe)
 		DEBUG("Using safe TX bursts%s",
 		      (force_safe ? " (forced)" : ""));
 		dev->tx_pkt_burst = &failsafe_tx_burst;
+		rte_eth_fp_ops[dev->data->port_id].tx_pkt_burst =
+			&failsafe_tx_burst;
 	} else if (!need_safe && safe_set) {
 		DEBUG("Using fast TX bursts");
 		dev->tx_pkt_burst = &failsafe_tx_burst_fast;
+		rte_eth_fp_ops[dev->data->port_id].tx_pkt_burst =
+			&failsafe_tx_burst_fast;
 	}
 	rte_wmb();
 }
-- 
2.25.1