On Thu, Feb 23, 2017 at 8:53 AM, Dave Barach (dbarach) <dbar...@cisco.com>
wrote:

>
> >>> Especially in multi-core situations, some care is required. I’m
> generally a fan of setting interfaces admin-down, vs. actually deleting
> them.
>

Ah, I see.  Check.

(So, for lack of atomic_inc() or visible locking of some form, the function
vnet_create_loopback_interface() is already not safely reentrant due to
the static u32 instance number.  Is this function possibly called in a
multi-core
senario? (I'm not sure what the global calling structure and threading model
around this code is.  (Sorry.)))


> And second, is there a bit-vector implementation around?
>
>
>
> >>> clib_bitmap_XXX(...), used in lots of places
>
>
>
> I would assume so and I just need to go looking...?
>

Sweet.  Thanks.


> I still need to resolve the name expectations; that is, expecting
>
> "Loopback" to be the base, and not "loop".  Does one of these
>
> options make more sense here?
>
>
>
> >>> This is an easy one. The string “loop” exists in exactly one place:
>
>
>
> static u8 *
>
> format_simulated_ethernet_name (u8 * s, va_list * args)
>
> {
>
>   u32 dev_instance = va_arg (*args, u32);
>
>   return format (s, "loop%d", dev_instance);
>
> }
>


Sure.  (Thanks.)  My real question is will existing VPP users and test
tolerate me just patching that to be s/loop/Loopback/.  I suspect "No".


> 1) Have the API create call supply the desired name directly,
>
>     defaulting to "loop"-names if none are specified.
>
>
>
> >>> Would it satisfy the cash customers to change the base string to
> “Loopback” - perhaps based on a config parameter - and add the desired
> instance number (not a free-form string) to the API? That will be less of a
> mess to implement.
>

Absolutely.  That was my preferred approach as well.


> 2) Have a loopback-module-global-ish config variable stating
>
>     to be in "loop" or "Loopback" mode.  Mode can be set via
>
>     new loopback API config call, or via VPP startup config setting.
>
>
>
> >>> could be done, of course, see (3) below...
>
>
>
> 3) Tell our users to get used to the New "loop" World Order? :-)
>
>
>
> >>> This would be a good topic for the vpp project call next week... I’ll
> add it to the agenda...
>
>
So, yeah, that would be good.  Sorry, I will be unable to make that meeting.


> PS -- At the risk of foretelling the future, bridge names are going to
>
>          have this same naming issue, right?  'Cuz those are next up!
>
>
>
> >>> Copying John Lo so he can stock up on headache remedies...
>

Excellent!

Thanks,
jdl
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