Re: [nft PATCH 3/7] libnftables: Introduce nft_ctx_flush_cache()

[Phil Sutter <phil@nwl.cc>]

Hi,

On Fri, Oct 20, 2017 at 02:13:26PM +0200, Pablo Neira Ayuso wrote:
> On Thu, Oct 19, 2017 at 10:18:43AM +0200, Phil Sutter wrote:
[...]
> > +void nft_ctx_flush_cache(struct nft_ctx *ctx)
> > +{
> > +	iface_cache_release();
> > +	cache_release(&ctx->cache);
> > +}
> 
> This flush allows us to release the cache, but nft_ctx_alloc()
> populates it. I'm missing something here, can we force a context
> repopulation?

No, nft_ctx_alloc() does not populate the cache, but just initialize
cache list head (which is not undone by cache_release()). Cache
population happens during command execution depending on whether a cache
is needed or not.

> If there is no usecase for this yet, I would keep this behind by now.

The use-case for the above is cli_complete(), which
explicitly drops the cache after execution of every command (probably
because it's potentially long-lived and therefore things might change in
background).

Cheers, Phil