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

[Jamal H. S. <ha...@zn...>]

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.

> -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) 

> BTW I had to use '-p6' to apply the patch

That should be fixable.

cheers,
jamal