From: Matt Domsch <Matt_Domsch@Dell•com>
To: Stephen Hemminger <shemminger@vyatta•com>
Cc: Narendra_K@Dell•com, netdev@vger•kernel.org,
Charles_Rose@Dell•com, Jordan_Hargrave@Dell•com
Subject: Re: [PATCH] Add firmware label support to iproute2
Date: Thu, 19 Aug 2010 17:18:50 -0500 [thread overview]
Message-ID: <20100819221850.GA20741@auslistsprd01.us.dell.com> (raw)
In-Reply-To: <20100819145308.0fa08522@nehalam>
On Thu, Aug 19, 2010 at 02:53:08PM -0700, Stephen Hemminger wrote:
> On Thu, 19 Aug 2010 16:33:14 -0500
> Matt Domsch <Matt_Domsch@Dell•com> wrote:
>
> > On Wed, Aug 18, 2010 at 02:41:24PM -0700, Stephen Hemminger wrote:
> > > The netdev_alias_to_kernelname should only happen after normal lookup failed.
> >
> > Stephen, can you enlighten me as to the "right" way to do interface
> > name lookups? While I can still find examples of parsing
> > /proc/net/dev, or globbing /sys/class/net/*, I expect these aren't the
> > preferred method anymore. Your own iproute2 suite uses RTM_GETLINK
> > netlink calls, though for the seeming simple case of "give me a list of all
> > interfaces", your path through there is far more capable (and
> > complex) than I would hope to need.
>
> There is no magic right way. We have to support multiple interfaces.
> I am really concerned that all this alias stuff will turn into a
> disaster when there are 10,000 interfaces (Vlans). The kernel has
> lots of tables and hashes to handle this but if the utilities
> are doing a dumb scan of all names it will not work.
I believe you proposed a lookup algorithm in each app, something like:
if exists(passed device name)
use it
else if (kernelname=netdev_alias_to_kernelname(passed device name))
use kernelname
so I'm looking for the "right" way to do these existance tests. I
agree iterating through all the interfaces should be avoided.
> Also burying logic in an external library seems problematic as
> well. The original sysfs library was a disaster for this.
> I want this to work but it has to have a simple interface that
> is not trying to hide things.
the library right now is all of:
422 netdevname.c
38 netdevname.h
with another 100 line app to print the mappings in both directions.
The interface is pretty simple too:
extern int netdev_alias_to_kernelname (const char *alias, char *kernelname);
struct netdev_alias {
char *name;
const char *namespace_name;
int is_descriptive; /* this may disappear yet */
struct netdev_alias *next;
};
extern int netdev_kernelname_to_aliases (const char *, struct netdev_alias **);
extern void free_netdev_aliases (struct netdev_alias *);
The common app usage will be to call netdev_alias_to_kernelname().
Only those apps that want to display the alternate names would use the
struct or other 2 functions.
Even though it's a small library, I do think it makes sense to make it
a library. I expect to add additional "namespaces" (e.g. "fw:Embedded
NIC 1" is the name of a device provided by the firmware. As I
mentioned in my talk at LinuxCon last week (slides at
http://domsch.com/linux/linuxcon10/) there could be other valid name
providers, and we'd like them to be usable without re-patching all the
applications again.
As always, I'm open to ideas.
Thanks,
Matt
--
Matt Domsch
Technology Strategist
Dell | Office of the CTO
next prev parent reply other threads:[~2010-08-19 22:18 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-12 17:35 [PATCH] Add firmware label support to iproute2 Narendra K
2010-08-12 18:10 ` Stephen Hemminger
2010-08-12 18:12 ` Stephen Hemminger
2010-08-13 12:36 ` Narendra_K
2010-08-18 21:41 ` Stephen Hemminger
2010-08-19 21:33 ` Matt Domsch
2010-08-19 21:53 ` Stephen Hemminger
2010-08-19 22:18 ` Matt Domsch [this message]
2010-08-25 22:03 ` Matt Domsch
2010-08-25 22:16 ` Greg KH
2010-08-26 14:10 ` Matt Domsch
2010-08-26 0:16 ` Stephen Hemminger
2010-08-26 15:01 ` Matt Domsch
2010-08-26 15:17 ` Loke, Chetan
2010-08-26 15:21 ` Stephen Hemminger
2010-08-26 15:38 ` Loke, Chetan
2010-08-27 7:54 ` Kay Sievers
2010-08-26 16:38 ` Matt Domsch
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