[PATCH v3] net/i40e: support enable/disable source pruning

[Morten Brørup]

> From: David Marchand [mailto:david.marchand at redhat.com]
> Sent: Monday, 17 April 2023 09.11
> 
> On Mon, Apr 17, 2023 at 3:58 AM Mingjin Ye <mingjinx.ye at intel.com> wrote:
> >
> > VRRP advertisement packets are dropped on i40e PF device because
> > when a MAC address is added to a device, packets originating from
> > that MAC address are dropped.
> > This patch adds a PMD specific API to enable/disable source
> > pruning to fix above issue.

Please amend the above sentence to mention that this patch changes the default behavior, e.g.:

This patch fixes the bug by disabling source pruning by default, and adds a PMD specific API to enable/disable source pruning.

> >
> > Bugzilla ID: 648
> >
> > Fixes: 94b3c1a72507 ("net/i40e: move testpmd commands")
> > Fixes: bce83974ba2c ("net/i40e: set Tx loopback from PF")
> > Fixes: 96974a6600ec ("net/i40e: move private APIs to a specific file")
> > Fixes: 689bba33272d ("i40e: add VEB switching support")
> > Fixes: 440499cf5376 ("net/i40e: support floating VEB")
> > Fixes: ef4c16fd9148 ("net/i40e: refactor RSS flow")
> 
> I see this as a new feature.

The main purpose of PMD change itself is to fix a bug (with low probability, but high impact if no workaround has been implemented in the application).

Adding the new function to set the source pruning behavior makes the code readable.

> 
> Please don't mark faulty any commit that touched this code (especially
> the ones that only moved code around).
> This is confusing.
> 
> 
> > Cc: stable at dpdk.org
> 
> Cc: stable maintainers.
> 
> This commit changes the default behavior, with no way to return to the
> old behavior (afaics).
> Backporting it poses a risk of breaking existing applications.

Correct, but it also fixes a bug that may go unnoticed in applications until they are deployed in networks where VRRP is used.

The default behavior was extremely strange, and the new default behavior makes perfect sense.

Acked-by: Morten Brørup <mb at smartsharesystems.com>

NB: I wanted to add some arguments in favor of this bugfix, which I consider important. Please do not ignore David's warnings!