Re: [PATCH] lib/ethdev: fix segfault in secondary process by validating dev_private pointer

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue, 22 Jul 2025 22:53:08 +0500
Khadem Ullah <14pwcse1224@uetpeshawar.edu.pk> wrote:

> Right, but performance and reliability are both important. While DPDK
> rightly prioritizes performance, some level of reliability should still be
> ensured, especially to catch known issues that could lead to instability.
> 
> On Tue, Jul 22, 2025, 22:38 Stephen Hemminger <stephen@networkplumber.org>
> wrote:
> 
> > On Tue, 22 Jul 2025 22:04:32 +0500
> > Khadem Ullah <14pwcse1224@uetpeshawar.edu.pk> wrote:
> >  
> > > Agree, but I think it's also a good practice to guard against known cases
> > > that are prone to crashes.  
> >
> >
> > Right but DPDK chooses performance over API safety.
> > For example rx/tx burst doesn't check args.
> >
> > The point is that as a library, if application is doing something wrong
> > returning error doesn't always help.
> >  

The problem is that all those values dev->data and private are shared
between processes without any locking. If the API's are going to MP safe
then they would require locking. The DPDK has made an explicit decision
to not use locking in ethdev control or data path.

You can get away with checking for dev->data being NULL on x86 where
there is data consistency. But on weakly ordered platforms that is not going
to work.