On Fri, Jan 18, 2002 at 03:23:09PM +0100, Harti Brandt wrote:
> On Fri, 18 Jan 2002, Ruslan Ermilov wrote:
> 
> RE>On Fri, Jan 18, 2002 at 10:41:58AM +0100, Harti Brandt wrote:
> RE>> On Fri, 18 Jan 2002, Ruslan Ermilov wrote:
> RE>>
> RE>> RE>On Thu, Jan 17, 2002 at 06:58:26PM +0100, Harti Brandt wrote:
> RE>> RE>>
> RE>> RE>> Hi,
> RE>> RE>>
> RE>> RE>> how is a daemon supposed to get informed that a network interface has been
> RE>> RE>> created? I had hoped, that an RTM_IFINFO message would be created on the
> RE>> RE>> routing socket, but this is not the case. If an interface is destroyed,
> RE>> RE>> the routing socket gets a message for whatever reason. Wouldn't it be
> RE>> RE>> simple to just create an RTM_IFINFO message?
> RE>> RE>>
> RE>> RE>It does get created (you can check with the ``route -vn monitor'' command),
> RE>> RE>but please see PR kern/33747 for one small pitfall.
> RE>>
> RE>> That's exactly what I did, but it doesn't work. The only places, that I
> RE>> can find when rt_ifmsg is called are:
> RE>>
> RE>>  - interface goes up     (if_route)
> RE>>  - interface goes down   (if_unroute)
> RE>>  - change MTU            (if_hwioctl)
> RE>>  - prom. mode            (ifpromisc)
> RE>>  - allmulti              (if_allmulti)
> RE>>
> RE>> No one seems to call it when I just create an interface. The RTM_IFINFO
> RE>> when I delete it probably comes from the if_unroute. The RTM_IFINFO you
> RE>> see for an ifconfig gif0 create is probably a side effect of setting the
> RE>> MTU or so.
> RE>>
> RE>> I think it would make sense to do an rt_ifmsg somehere in
> RE>> if_attach/if_detach.
> RE>>
> RE>OK, I will send a patch within an hour or so.  NetBSD already
> RE>has something to address this.
> 
> I just had a look at this and, yes, that's what I mean.
> 
I've just committed this feature.

> Just one question:
> is there any locking that does a user process prevent from seeing the
> interface still on the interface list after the message is sent, but
> before the interface is removed from the list? (I mean on an SMP system).
> The DEPARTURE message is sent before the interface is unlinked from the
> list.
> 
In -STABLE, splnet() does the necessary locking.  In SMPng'ed -CURRENT,
I do not believe any ifnet-related mutexes code was committed.  I think
that the locking is done with Giant at the moment, but I may be wrong.
In any case, the code I have committed does not make things any worse,
as if_detach() should be able to modify the ifnet list of interfaces,
and any ifnet-traversing code should block if the modification is in
progress.


Cheers,
-- 
Ruslan Ermilov          Oracle Developer/DBA,
[EMAIL PROTECTED]           Sunbay Software AG,
[EMAIL PROTECTED]          FreeBSD committer,
+380.652.512.251        Simferopol, Ukraine

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