On Tue, Mar 5, 2024 at 6:28 PM David Wei <dw@xxxxxxxxxxx> wrote:
>
> On 2024-03-04 18:01, Mina Almasry wrote:
> > + if (pool->p.queue)
> > + binding = READ_ONCE(pool->p.queue->binding);
> > +
> > + if (binding) {
> > + pool->mp_ops = &dmabuf_devmem_ops;
> > + pool->mp_priv = binding;
> > + }
>
> This is specific to TCP devmem. For ZC Rx we will need something more
> generic to let us pass our own memory provider backend down to the page
> pool.
>
> What about storing ops and priv void ptr in struct netdev_rx_queue
> instead? Then we can both use it.
Yes, this is dmabuf specific, I was thinking you'd define your own
member of netdev_rx_queue, and then add something like this to
page_pool_init:
+ if (pool->p.queue)
+ io_uring_metadata = READ_ONCE(pool->p.queue->io_uring_metadata);
+
+ /* We don't support rx-queues that are configured for both
io_uring & dmabuf binding */
+ BUG_ON(io_uring_metadata && binding);
+
+ if (io_uring_metadata) {
+ pool->mp_ops = &io_uring_ops;
+ pool->mp_priv = io_uring_metadata;
+ }
I.e., we share the pool->mp_ops and the pool->mp_priv but we don't
really need to share the same netdev_rx_queue member. For me it's a
dma-buf specific data structure (netdev_dmabuf_binding) and for you
it's something else.
page_pool_init() probably needs to validate that the queue is
configured for dma-buf or io_uring but not both. If it's configured
for both then the user is doing something funky we shouldn't support.
Perhaps I can make the intention clearer by renaming 'binding' to
something more specific to dma-buf like queue->dmabuf_binding, to make
it clear that this is the dma-buf binding and not some other binding
like io_uring?
--
Thanks,
Mina
