From: "Michael S. Tsirkin" <mst@redhat.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jiri Pirko <jpirko@redhat.com>,
netdev@vger.kernel.org, shimoda.hiroaki@gmail.com,
virtualization@lists.linux-foundation.org,
danny.kukawka@bisect.de, edumazet@google.com,
davem@davemloft.net
Subject: Re: [patch net-next 1/4] net: introduce new priv_flag indicating iface capable of change mac when running
Date: Thu, 28 Jun 2012 23:32:34 +0300 [thread overview]
Message-ID: <20120628203234.GA15451@redhat.com> (raw)
In-Reply-To: <1340897092.13187.110.camel@edumazet-glaptop>
On Thu, Jun 28, 2012 at 05:24:52PM +0200, Eric Dumazet wrote:
> On Thu, 2012-06-28 at 16:10 +0200, Jiri Pirko wrote:
> > Introduce IFF_LIFE_ADDR_CHANGE priv_flag and use it to disable
> > netif_running() check in eth_mac_addr()
> >
> > Signed-off-by: Jiri Pirko <jpirko@redhat.com>
> > ---
> > include/linux/if.h | 2 ++
> > net/ethernet/eth.c | 2 +-
> > 2 files changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/if.h b/include/linux/if.h
> > index f995c66..fd9ee7c 100644
> > --- a/include/linux/if.h
> > +++ b/include/linux/if.h
> > @@ -81,6 +81,8 @@
> > #define IFF_UNICAST_FLT 0x20000 /* Supports unicast filtering */
> > #define IFF_TEAM_PORT 0x40000 /* device used as team port */
> > #define IFF_SUPP_NOFCS 0x80000 /* device supports sending custom FCS */
> > +#define IFF_LIFE_ADDR_CHANGE 0x100000 /* device supports hardware address
> > + * change when it's running */
> >
> >
> > #define IF_GET_IFACE 0x0001 /* for querying only */
> > diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
> > index 36e5880..8f8ded4 100644
> > --- a/net/ethernet/eth.c
> > +++ b/net/ethernet/eth.c
> > @@ -283,7 +283,7 @@ int eth_mac_addr(struct net_device *dev, void *p)
> > {
> > struct sockaddr *addr = p;
> >
> > - if (netif_running(dev))
> > + if (!(dev->priv_flags & IFF_LIFE_ADDR_CHANGE) && netif_running(dev))
> > return -EBUSY;
> > if (!is_valid_ether_addr(addr->sa_data))
> > return -EADDRNOTAVAIL;
>
> Since the memcpy() is not atomic, there is a small window where a reader
> could get a half-changed mac address. I guess its a detail.
>
At least for virtio nothing changes - we had this bug forever.
How'd you fix this?
--
MST
next prev parent reply other threads:[~2012-06-28 20:32 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-28 14:10 [patch net-next 0/4] net: introduce and use IFF_LIFE_ADDR_CHANGE Jiri Pirko
2012-06-28 14:10 ` [patch net-next 1/4] net: introduce new priv_flag indicating iface capable of change mac when running Jiri Pirko
2012-06-28 15:24 ` Eric Dumazet
2012-06-28 20:32 ` Michael S. Tsirkin [this message]
2012-06-28 22:17 ` Ben Hutchings
2012-06-29 6:41 ` Jiri Pirko
2012-06-28 14:10 ` [patch net-next 2/4] virtio_net: use IFF_LIFE_ADDR_CHANGE priv_flag Jiri Pirko
2012-06-28 19:21 ` Michael S. Tsirkin
2012-06-28 14:10 ` [patch net-next 3/4] team: " Jiri Pirko
2012-06-28 14:10 ` [patch net-next 4/4] dummy: " Jiri Pirko
2012-06-28 14:10 ` Jiri Pirko
2012-06-28 15:15 ` [patch net-next 0/4] net: introduce and use IFF_LIFE_ADDR_CHANGE Richard Cochran
2012-06-28 15:41 ` Jiri Pirko
2012-06-28 15:15 ` Richard Cochran
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