Re: [PATCH net-next v24 03/13] netdev: support binding dma-buf to netdevice

[Jakub Kicinski <kuba@kernel.org>]

On Sat, 31 Aug 2024 00:43:03 +0000 Mina Almasry wrote:
> Add a netdev_dmabuf_binding struct which represents the
> dma-buf-to-netdevice binding. The netlink API will bind the dma-buf to
> rx queues on the netdevice. On the binding, the dma_buf_attach
> & dma_buf_map_attachment will occur. The entries in the sg_table from
> mapping will be inserted into a genpool to make it ready
> for allocation.
> 
> The chunks in the genpool are owned by a dmabuf_chunk_owner struct which
> holds the dma-buf offset of the base of the chunk and the dma_addr of
> the chunk. Both are needed to use allocations that come from this chunk.
> 
> We create a new type that represents an allocation from the genpool:
> net_iov. We setup the net_iov allocation size in the
> genpool to PAGE_SIZE for simplicity: to match the PAGE_SIZE normally
> allocated by the page pool and given to the drivers.
> 
> The user can unbind the dmabuf from the netdevice by closing the netlink
> socket that established the binding. We do this so that the binding is
> automatically unbound even if the userspace process crashes.
> 
> The binding and unbinding leaves an indicator in struct netdev_rx_queue
> that the given queue is bound, and the binding is actuated by resetting
> the rx queue using the queue API.
> 
> The netdev_dmabuf_binding struct is refcounted, and releases its
> resources only when all the refs are released.

Reviewed-by: Jakub Kicinski <kuba@kernel.org>