Hi Gaetan
From: Gaëtan Rivet, Thursday, February 8, 2018 7:20 PM
> Hi Matan,
>
> Thanks for dealing with this.
>
> On Thu, Feb 08, 2018 at 04:34:12PM +0000, Matan Azrad wrote:
> > Fail-safe PMD uses per sub-device flag called "remove" to indicate the
> > scope where the sub-device isn't synchronized with the fail-safe state.
> >
> > This flag is set when fail-safe gets RMV notification about the
> > physical removal of the sub-device and should be unset when the
> > sub-device completes all the configurations cause it to arrive to the
> > fail-safe state.
> >
> > The previous code wrongly unsets the flag after calling to the
> > sub-device PMD dev_configure() operation and before all the
> > configurations were done.
> >
> > Change the remove flag unsetting to be only after the sub-device
> > successes to arrive to the fail-safe state.
> >
>
> I'm not sure this is the right way to do this.
> I think it's clear that it was a mistake to set sdev->remove to 0 only during
> fs_dev_configure.
>
> The flag itself only means "there is something to be done on this device,
> please clean up".
>
> Once the clean-up has happened, then the flag is not necessary anymore
> and should be reset.
>
> So I thought that this fix would actually put the flag reset within
> fs_dev_remove, right before reinstalling the hotplug alarm.
>
> At this point, the device state would have been set back to DEV_UNDEFINED,
> so the remove flag is unnecessary for any operation trying to avoid
> unplugged slaves.
>
> The "remove" flag is initialized at 0 when sub-devices are allocated (during
> fail-safe init). This means that there would be a difference in the state of
> the
> slave between its first initialization and any subsequent init, after one
> successful plugout.
>
But what's about plug-in process?
Do you want to allow control commands for a sub-device while it is plugging-in?
Unset the remove flag in fs_dev_remove allows to control commands to occur in
parallel to plug in process.
Maybe the name of the flag should be changed to unsynchronized.
> > Fixes: a46f8d5 ("net/failsafe: add fail-safe PMD")
> > Cc: sta...@dpdk.org
> >
> > Signed-off-by: Matan Azrad <ma...@mellanox.com>
> > ---
> > drivers/net/failsafe/failsafe_ether.c | 2 ++
> > drivers/net/failsafe/failsafe_ops.c | 2 +-
> > 2 files changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/failsafe/failsafe_ether.c
> > b/drivers/net/failsafe/failsafe_ether.c
> > index 4c6e938..ca42376 100644
> > --- a/drivers/net/failsafe/failsafe_ether.c
> > +++ b/drivers/net/failsafe/failsafe_ether.c
> > @@ -377,6 +377,8 @@
> > i);
> > goto err_remove;
> > }
> > + if (PRIV(dev)->state < DEV_STARTED)
> > + sdev->remove = 0;
>
> Here the remove flag should already be 0. If it isn't, this is a
> (logical) bug, which should be properly addressed instead of patched in this
> way.
Same answer as above.
> > }
> > }
> > /*
> > diff --git a/drivers/net/failsafe/failsafe_ops.c
> > b/drivers/net/failsafe/failsafe_ops.c
> > index 7a67e16..a7c2dba 100644
> > --- a/drivers/net/failsafe/failsafe_ops.c
> > +++ b/drivers/net/failsafe/failsafe_ops.c
> > @@ -131,7 +131,6 @@
> > dev->data->dev_conf.intr_conf.lsc = 0;
> > }
> > DEBUG("Configuring sub-device %d", i);
> > - sdev->remove = 0;
>
> This is correct.
>
> > ret = rte_eth_dev_configure(PORT_ID(sdev),
> > dev->data->nb_rx_queues,
> > dev->data->nb_tx_queues,
> > @@ -197,6 +196,7 @@
> > return ret;
> > }
> > sdev->state = DEV_STARTED;
> > + sdev->remove = 0;
>
> This seems unnecessary, if this operation was already performed once the
> device has been properly removed.
Same answer as above.
> > }
> > if (PRIV(dev)->state < DEV_STARTED)
> > PRIV(dev)->state = DEV_STARTED;
> > --
> > 1.8.3.1
> >
>
> --
> Gaëtan Rivet
> 6WIND
