Re: [mpls-linux-devel] Current state of dst stacking on davem implementation

[James R. L. <jl...@mi...>]

On Wed, Mar 03, 2004 at 06:21:08AM -0500, Jamal Hadi Salim wrote:
> On Mon, 2004-03-01 at 00:03, James R. Leu wrote:
> 
> > Items left to be resolved:
> > -correct l2c command line for input definition?  (are we open for discussing
> >  changes?)
> 
> I will look at it and get back to you.

I wonder if there is a way to change the nhlfe options so that they make more
sense when defining a local delivery NHLFE.

> > -correct model for refcnting nhlfe's.  I have an idea:
> >    -'imagined' refcnt for holding nhlfe in hash table, no actual
> >     inc or dec when adding/deleting to hash table.  This way a simple
> >     check for refcnt != 0 will tell if some other layer is using the
> >     nhlfe (ILM, IPv4 rt_cache/route table, IPv6 route table, etc).  Deletes
> >     are denied until refcnt == 0, at which time a dst_free is executed.
> >    -question: OK to let a dst_entry have refcnt of 0?  Do I need to handle
> >     any special cases in the dst_ops to account for the refcnt != 0 cases?
> >    -I have this implemented on my code and am doing long term testing (>24hrs)
> >     to see if anything weird happens to ths refcnting.
> 
> I havent looked at code, but:
> As a general rule, unless you have no choice, it is safer to just use
> refcounting for atomicity purposes (eg SMP safety - the stack is pretty
> much reentrant and could run concurently on multiple processors) 

I think I have a scheme that works, I'll post an updated diff this weekend.

> > BTW I had to use '-p6' to apply the patch
> 
> That should be fixable.

This is from using p4's diff to generate the patch.

> 
> cheers,
> jamal
> 
> 
> 
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-- 
James R. Leu
jl...@mi...