RE: [PATCH] app/testpmd: support retrying device stop

[Dariusz Sosnowski <dsosnowski@nvidia.com>]

> -----Original Message-----
> From: Ferruh Yigit <ferruh.yigit@amd.com>
> Sent: Friday, July 5, 2024 13:29
> To: Stephen Hemminger <stephen@networkplumber.org>; Maayan Kashani
> <mkashani@nvidia.com>
> Cc: dev@dpdk.org; Dariusz Sosnowski <dsosnowski@nvidia.com>; Raslan
> Darawsheh <rasland@nvidia.com>; Aman Singh <aman.deep.singh@intel.com>;
> Yuying Zhang <yuying.zhang@intel.com>
> Subject: Re: [PATCH] app/testpmd: support retrying device stop
> 
> On 6/3/2024 6:09 PM, Stephen Hemminger wrote:
> > On Sun, 2 Jun 2024 13:30:35 +0300
> > Maayan Kashani <mkashani@nvidia.com> wrote:
> >
> >> From: Dariusz Sosnowski <dsosnowski@nvidia.com>
> >>
> >> In some cases rte_eth_dev_stop() can fail with EBUSY error code
> >> meaning that port cannot be stopped, because of other resources
> >> referencing this port and port must be stopped again after these resources are
> freed.
> >>
> >> This patch adds handling of EBUSY error code on port stop to testpmd.
> >>
> >> Signed-off-by: Dariusz Sosnowski <dsosnowski@nvidia.com>
> >
> > What causes EBUSY. Seems like a driver bug or a test scenario problem.
> > You can't expect every DPDK application to retry.
> >
> 
> 'rte_eth_dev_stop()' returning EBUSY anticipates this kind of usage already.
> 
> But I also agree we should avoid propagating driver issues to the application, that
> is why it is better to clarify motivation of this patch, why specific driver returns
> EBUSY on stop.

Agreed regarding not propagating it to application.

Currently mlx5 PMD can return EBUSY because of a limitation in the PMD,
regarding ordering of start/stop operations of representor ports
(http://git.dpdk.org/dpdk/tree/drivers/net/mlx5/mlx5_trigger.c#n1417).
We should eventually resolve that limitation in PMD.

I think we can drop this patch.

Best regards,
Dariusz Sosnowski