Re: [PATCH v3 1/5] failsafe: fix segfault on hotplug event

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue, 29 Nov 2022 09:48:29 -0500
Luc Pelletier <lucp.at.work@gmail.com> wrote:

> 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 "unsafe" rx/tx functions were completely
> removed. The "safe" functions are now always used. Modifying the rx/tx
> functions on-the-fly is not supported by DPDK, so this is the correct
> approach and should have very minimal impact on performance.
> 
> Fixes: 7a0935239b9e ("ethdev: make fast-path functions to use new flat array")
> Cc: Konstantin Ananyev <konstantin.ananyev@huawei.com>
> Cc: stable@dpdk.org
> 
> Signed-off-by: Luc Pelletier <lucp.at.work@gmail.com>


I don't use or have way to test failsafe anymore.
But wanted to give a try at reviewing this.
This version does not apply to current code base.
If still interested, please rebase and resubmit.