> 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 7a0935239b, 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.
It is not recommended way to update rte_eth_fp_ops[] contents directly.
There are eth_dev_fp_ops_setup()/ eth_dev_fp_ops_reset() that supposed
to be used for that.
About the fix itself - while it might help till some extent,
I think it will not remove the problem completely.
There still remain a race-condition between rte_eth_rx_burst() and
failsafe_eth_rmv_event_callback().
Right now DPDK doesn't support switching PMD fast-ops functions (or updating
rxq/txq data)
on the fly.
> Fixes: 7a0935239b ("ethdev: make fast-path functions to use new flat array")
> Cc: Konstantin Ananyev <konstantin.anan...@intel.com>
> Cc: sta...@dpdk.org
>
> Signed-off-by: Luc Pelletier <lucp.at.w...@gmail.com>
> ---
> 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
