On 11/3/25 23:41, David Wei wrote:

Add two refcounts to struct io_zcrx_ifq to reverse the refcounting
relationship i.e. rings now reference ifqs instead. As a result of this,

Note, you don't need the 2nd refcount in this patch as there is
only one io_uring using it. I hope not, but there is a chance
we might need to backport it, which is why it's midly preferably
to be kept separate.

remove ctx->refs that an ifq holds on a ring via the page pool memory
provider.

Nice!

The first ref is ifq->refs, held by internal users of an ifq, namely
rings and the page pool memory provider associated with an ifq. This is
needed to keep the ifq around until the page pool is destroyed.

The second ref is ifq->user_refs, held by userspace facing users like
rings. For now, only the ring that created the ifq will have a ref, but
with ifq sharing added, this will include multiple rings.

ifq->refs will be 1 larger than ifq->user_refs, with the extra ref held

Can be larger than +1 as there might be multiple page pools
referring to it.

by the page pool. Once ifq->user_refs falls to 0, the ifq is cleaned up
including destroying the page pool. Once the page pool is destroyed,
ifq->refs will fall to 0 and free the ifq.

-- 
Pavel Begunkov