Re: [dpdk-dev] [PATCH 2/3] devargs: delay freeing previous devargs when overriding them

[Thomas Monjalon <thomas@monjalon.net>]

05/11/2018 09:25, Stojaczyk, Dariusz:
> Hi Thomas,
> 
> From: Thomas Monjalon [mailto:thomas@monjalon.net]
> > 05/11/2018 08:04, Darek Stojaczyk:
> > > -int __rte_experimental
> > > -rte_devargs_insert(struct rte_devargs *da)
> > > +void __rte_experimental
> > > +rte_devargs_insert(struct rte_devargs *da, struct rte_devargs
> > **prev_da)
> > 
> > You should update the API section of the release notes.
> 
> Even for experimental API? OK, I didn't know it's needed.

Yes, even for experimental API, the API changes must documented.

> > >  {
> > > -       int ret;
> > > +       struct rte_devargs *d;
> > > +       void *tmp;
> > > +
> > > +       *prev_da = NULL;
> > > +       TAILQ_FOREACH_SAFE(d, &devargs_list, next, tmp) {
> > > +               if (strcmp(d->bus->name, da->bus->name) == 0 &&
> > > +                   strcmp(d->name, da->name) == 0) {
> > > +                       TAILQ_REMOVE(&devargs_list, d, next);
> > > +                       *prev_da = d;
> > > +                       break;
> > > +               }
> > > +       }
> > >
> > > -       ret = rte_devargs_remove(da);
> > > -       if (ret < 0)
> > > -               return ret;
> > 
> > Why not updating rte_devargs_remove instead of duplicating its code?
> 
> We still want to preserve the functionality of rte_devargs_remove.
> rte_devargs_remove does TAILQ_REMOVE + free; rte_devargs_insert does just TAILQ_REMOVE. (I think I also forgot to update rte_devargs_insert documentation, I'll  do that in V2)

Yes, because of the rollback, OK.
Please mention in devargs_insert doc that the old devargs
can be used for rollback.

> Since you've mentioned it:
> Eventually I'd see rte_devargs_remove to accept the exact same devargs parameter that was passed to rte_devargs_insert. Then rte_devargs_remove wouldn't do any sort of lookup. Maybe additional rte_devargs_find(const char *name) could be added for existing cases where the original devargs struct is not available. However, I'm not familiar enough with this code to perform the refactor and am just trying to fix the stuff. Still, how does it sound?

I think we can keep it as is.

We can re-think the whole thing in the next release.
I think we should not play with devargs list as we do.
There should be only lists for scanned devices of each bus and that's all.