[dpdk-dev] [PATCH] ethdev: fix setting of MAC address
Olivier MATZ
olivier.matz at 6wind.com
Tue Dec 19 10:29:33 CET 2017
Hi,
On Mon, Dec 18, 2017 at 02:38:55PM +0300, Andrew Rybchenko wrote:
> On 12/18/2017 01:53 PM, Igor Ryzhov wrote:
> >
> > On Mon, Dec 18, 2017 at 1:35 PM, Andrew Rybchenko
> > <arybchenko at solarflare.com <mailto:arybchenko at solarflare.com>> wrote:
> >
> > On 12/14/2017 08:15 PM, Olivier Matz wrote:
> >
> > From: Laurent Hardy <laurent.hardy at 6wind.com
> > <mailto:laurent.hardy at 6wind.com>>
> >
> > When a new mac address is set, it is saved in dev->data->mac_addrs
> > before the ethdev handler is called.
> >
> > First, it is inconsistent with the other ethdev functions
> > rte_eth_dev_mac_addr_remove() and rte_eth_dev_mac_addr_add().
> >
> > Moreover, it prevents the drivers from wrongly comparing the
> > old address
> > and the new one, like it's done in i40evf driver:
> >
> > if (is_same_ether_addr(mac_addr, dev->data->mac_addrs))
> > return;
> >
> > Fixes: 943c2d899a0c ("net/i40e: set VF MAC from VF")
> > Fixes: 854d8ad4ef68 ("ethdev: add default mac address modifier")
> > Cc: stable at dpdk.org <mailto:stable at dpdk.org>
> >
> > Signed-off-by: Laurent Hardy <laurent.hardy at 6wind.com
> > <mailto:laurent.hardy at 6wind.com>>
> > ---
> > lib/librte_ether/rte_ethdev.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/lib/librte_ether/rte_ethdev.c
> > b/lib/librte_ether/rte_ethdev.c
> > index 4f492e3db..297c02a54 100644
> > --- a/lib/librte_ether/rte_ethdev.c
> > +++ b/lib/librte_ether/rte_ethdev.c
> > @@ -2643,11 +2643,11 @@
> > rte_eth_dev_default_mac_addr_set(uint16_t port_id, struct
> > ether_addr *addr)
> > dev = &rte_eth_devices[port_id];
> > RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->mac_addr_set,
> > -ENOTSUP);
> > + (*dev->dev_ops->mac_addr_set)(dev, addr);
> > +
> > /* Update default address in NIC data structure */
> > ether_addr_copy(addr, &dev->data->mac_addrs[0]);
> > - (*dev->dev_ops->mac_addr_set)(dev, addr);
> > -
> > return 0;
> > }
> >
> >
> > NACK, unfortunately it will break net/sfc in one of branches when
> > a new MAC
> > is set using restart. It relies on the fact that a new MAC is
> > already available in
> > device data.
> >
> >
> > Hello Andrew,
> >
> > Don't you think that it's not correct that net/sfc works that way?
> >
> > If we go further, dev->dev_ops->mac_addr_set not only should be called
> before ether_addr_copy.
> > It should return status code, and in case of error ether_addr_copy
> > shouldn't be
> called at all.
> > Am I wrong?
Yes, I also have the same feeling.
> Current behaviour is convenient. Alternative will require copy of MAC
> address
> to set in device private data and one more copy in the function to rollback
> in
> the case of failure. If there are good reasons to change behaviour, I don't
> mind but PMDs should be reviewed carefully and fixed before the change.
Right. The first version of the patch was just a fix of the i40e code,
which was of course less risky. But we finally decided to to that way
for consistency.
I will review the other PMDs and send a v2 that should not break
them. If you have any guidelines for net/sfc, they will be welcome :)
Thanks for the review.
Olivier
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