Re: HEADSUP: internal network interface changes

On Fri, Jun 10, 2005 at 09:26:00AM -0700, Brooks Davis wrote:
> Look out! :-)
> 
> This change is incoming sortly (pending final cvs updates).

I've committed the change bumping __FreeBSD_version.  Hopefully the
ride won't be too bumpy.  If you have any problems, please report them
on -current as well as to me directly.  Most problems should be fairly
simple to fix.  I will be checking my e-mail regularly for at least the
next 14 hours.

-- Brooks

> On Wed, Jun 08, 2005 at 11:44:52PM -0700, Brooks Davis wrote:
> > I plan to commit a major rework of network interface related storage
> > Friday morning PDT.  This is a massive change touching every network
> > driver in the system.  This change was discussed at the BSDCan dev
> > summit and derives from discussions at EuroBSDCon on dealing with
> > dynamic network devices.  You can view the diff at:
> > 
> > http://people.freebsd.org/~brooks/patches/ifnet.diff
> > 
> > I'm not posting the diff to the list as it is nearly 700K.  Below, you
> > will find the diff to ifnet(9) for a more technical view of the API
> > change.
> > 
> > In short, the change removes the embedded struct ifnet and layer 2 common
> > structures (struct arpcom, struct ifatm, struct sppp, etc) from driver
> > softcs and replaces them with a struct ifnet pointer which is allocated
> > with a new function, if_alloc which takes an interface type.  For
> > certain types, if_alloc also fills in the new struct ifnet member,
> > if_l2com with an initialized layer 2 common structure.
> > 
> > The benefits of this change are:
> >  - The size of struct ifnet and the layer 2 common structures is no
> >    longer part of the network interface ABI.  This means we add
> >    features to the generic interface code so long as they do not require
> >    action on the part of the driver without breaking the ABI.
> >  - Since storage is no longer tied to the softc, we will able to
> >    reference count struct ifnet more easily which is a prerequisite for
> >    fixing the panics on removing an interface which is configured with
> >    dummynet.
> >  - This patch eliminates many ugly casts and the historically weakly
> >    documented requirement that softc's be castable to ifnet's and
> >    arpcom's.
> > 
> > Things to note about this change:
> >  - External drivers including those in ports will panic if loaded until
> >    they are converted to the new API.
> > 
> > Things to note about this patch:
> >  - There are nearly 100 drivers in the tree and I only use a small set
> >    of them so there are likely to be some small bugs in this patch.  The
> >    changes were mostly mechanical, but varying naming conventions, plus
> >    the occasional driver written entirely from scratch introduce the
> >    possibility of errors.  Use care when updating, particularly with
> >    remote systems.
> >  - In most cases, this patch does not address the issue of keeping
> >    source compatible with previous releases or other systems.  I will
> >    supply patches to do so in any case where there is a need, but I
> >    intend to wait until after committing to do so.  I hope the set of
> >    drivers requiring these changes will be small.
> > 
> > -- Brooks
> > 
> > P.S. the posted patch contains a bug in the udav driver.  It will be
> > fixed before commit.
> > 
> > --- freebsd/share/man/man9/ifnet.9	Sun Jun  5 13:33:05 2005
> > +++ ifnet/share/man/man9/ifnet.9	Sun Jun  5 20:20:03 2005
> > _at__at_ -46,9 +46,17 _at__at_
> >  .In net/if_types.h
> >  .\"
> >  .Ss "Interface Manipulation Functions"
> > +.Ft "struct ifnet *"
> > +.Fn if_alloc "u_char type"
> >  .Ft void
> >  .Fn if_attach "struct ifnet *ifp"
> >  .Ft void
> > +.Fn if_detach "struct ifnet *ifp"
> > +.Ft void
> > +.Fn if_free "struct ifnet *ifp"
> > +.Ft void
> > +.Fn if_free_type "struct ifnet *ifp" "u_char type"
> > +.Ft void
> >  .Fn if_down "struct ifnet *ifp"
> >  .Ft int
> >  .Fn ifioctl "struct socket *so" "u_long cmd" "caddr_t data" "struct thread *td"
> > _at__at_ -219,6 +227,11 _at__at_
> >  .Pq Vt "void *"
> >  A pointer to the driver's private state block.
> >  (Initialized by driver.)
> > +.It Va if_l2com
> > +.Pq Vt "void *"
> > +A pointer to the common data for the interface's layer 2 protocol.
> > +(Initialized by
> > +.Fn if_alloc .)
> >  .It Va if_link
> >  .Pq Fn TAILQ_ENTRY ifnet
> >  .Xr queue 3
> > _at__at_ -270,6 +283,8 _at__at_
> >  to refer to a particular interface by index
> >  (see
> >  .Xr link_addr 3 ) .
> > +(Initialized by
> > +.Fn if_alloc .)
> >  .It Va if_timer
> >  .Pq Vt short
> >  Number of seconds until the watchdog timer
> > _at__at_ -988,6 +1003,14 _at__at_
> >  .El
> >  .Ss Interface Manipulation Functions
> >  .Bl -ohang -offset indent
> > +.It Fn if_alloc
> > +Allocate and initalize an
> > +.Fa ifp .
> > +Initalization includes the allocation of an interface index and may
> > +include the allocation of a
> > +.Fa type
> > +specific structure in
> > +.Va if_l2com .
> >  .It Fn if_attach
> >  Link the specified interface
> >  .Fa ifp
> > _at__at_ -999,6 +1022,29 _at__at_
> >  (A pointer to
> >  this address structure is saved in the global array
> >  .Va ifnet_addrs . )
> > +The
> > +.Fa ifp
> > +must have been allocted by
> > +.Fn if_alloc .
> > +.It Fn if_detach
> > +Shutdown and unlink the specified
> > +.Fa ifp
> > +from the interface list.
> > +.It Fn if_free
> > +Free the given
> > +.Fa ifp
> > +back to the system.
> > +The interface must have been previously detached if it was ever attached.
> > +.It Fn if_free_type
> > +Identical to
> > +.Fn if_free
> > +except that the given
> > +.Fa type
> > + is used to free 
> > + .Va if_l2com
> > + instead of the type in
> > + .Va if_type .
> > + This is intended for use with drivers that change their interface type.
> >  .It Fn if_down
> >  Mark the interface
> >  .Fa ifp
> > 
> > -- 
> > Any statement of the form "X is the one, true Y" is FALSE.
> > PGP fingerprint 655D 519C 26A7 82E7 2529  9BF0 5D8E 8BE9 F238 1AD4
> 
> 
> -- 
> Any statement of the form "X is the one, true Y" is FALSE.
> PGP fingerprint 655D 519C 26A7 82E7 2529  9BF0 5D8E 8BE9 F238 1AD4


-- 
Any statement of the form "X is the one, true Y" is FALSE.
PGP fingerprint 655D 519C 26A7 82E7 2529  9BF0 5D8E 8BE9 F238 1AD4