From: James Prestwood <prestwoj@gmail.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org, johannes@sipsolutions.net
Subject: Re: [RFC 1/1] net: move IFF_LIVE_ADDR_CHANGE to public flag
Date: Thu, 04 Aug 2022 12:49:01 -0700 [thread overview]
Message-ID: <f03b4330c7e9d131d9ad198900a3370de4508304.camel@gmail.com> (raw)
In-Reply-To: <b6b11b492622b75e50712385947e1ba6103b8e44.camel@gmail.com>
Forgot to CC Johannes.
Thanks
On Thu, 2022-08-04 at 12:23 -0700, James Prestwood wrote:
> On Thu, 2022-08-04 at 11:43 -0700, Jakub Kicinski wrote:
> > On Thu, 4 Aug 2022 10:43:07 -0700 James Prestwood wrote:
> > > By exposing IFF_LIVE_ADDR_CHANGE to userspace it at least gives
> > > an
> > > indication that we can successfully randomize the address and
> > > connect. In the worst case address randomization can be avoided
> > > ahead of time. A secondary win is also time, since userspace can
> > > avoid a power down unless its required which saves some time.
> >
> > It's not a generic thing tho, it's most of an implicit argument
> > to eth_mac_addr(). Not all netdevs are Ethernet.
> >
> > The semantics in wireless are also a little stretched because
> > normally
> > if the flag is not set the netdev will _refuse_ (-EBUSY) to change
> > the
> > address while running, not do some crazy fw reset.
>
> Sorry if I wasn't clear, but its not nl80211 doing the fw reset
> automatically. The wireless subsystem actually completely disallows a
> MAC change if the device is running, this flag isn't even checked.
> This
> means userspace has to bring the device down itself, then change the
> MAC.
>
> I plan on also modifying mac80211 to first check this flag and allow
> a
> live MAC change if possible. But ultimately userspace still needs to
> be
> aware of the support.
>
> >
> > Perhaps we should wait for Johannes to return form vacation but my
> > immediate reaction would be to add a knob (in wireless?) that
> > controls
> > whether the reset dance is allowed.
>
> Ok sounds good. Lets see what Johannes has to say.
>
next prev parent reply other threads:[~2022-08-04 19:50 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-04 17:43 [RFC 0/1] Move IFF_LIVE_ADDR_CHANGE to public flag James Prestwood
2022-08-04 17:43 ` [RFC 1/1] net: move " James Prestwood
2022-08-04 17:59 ` Stephen Hemminger
2022-08-04 19:29 ` James Prestwood
2022-08-04 18:43 ` Jakub Kicinski
2022-08-04 19:23 ` James Prestwood
2022-08-04 19:49 ` James Prestwood [this message]
2022-08-09 19:04 ` Johannes Berg
2022-08-10 16:26 ` James Prestwood
2022-08-10 17:17 ` Johannes Berg
2022-08-10 17:36 ` Jakub Kicinski
2022-08-10 19:35 ` James Prestwood
2022-08-04 20:49 ` [RFC 0/1] Move " Andrew Lunn
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