On Wed, Aug 09, 2023 at 06:57:38PM -0700, 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 > an rx queue 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: > page_pool_iov. We setup the page_pool_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, but the binding doesn't take effect until > the driver actually reconfigures its queues, and re-initializes its page > pool. This issue/weirdness is highlighted in the memory provider > proposal[1], and I'm hoping that some generic solution for all > memory providers will be discussed; this patch doesn't address that > weirdness again. > > The netdev_dmabuf_binding struct is refcounted, and releases its > resources only when all the refs are released. > > [1] https://lore.kernel.org/netdev/20230707183935.997267-1-kuba@xxxxxxxxxx/ > > Signed-off-by: Willem de Bruijn <willemb@xxxxxxxxxx> > Signed-off-by: Kaiyuan Zhang <kaiyuanz@xxxxxxxxxx> > > Signed-off-by: Mina Almasry <almasrymina@xxxxxxxxxx> > --- > include/linux/netdevice.h | 57 ++++++++++++ > include/net/page_pool.h | 27 ++++++ > net/core/dev.c | 178 ++++++++++++++++++++++++++++++++++++++ > net/core/netdev-genl.c | 101 ++++++++++++++++++++- > 4 files changed, 361 insertions(+), 2 deletions(-) <...> > +void __netdev_devmem_binding_free(struct netdev_dmabuf_binding *binding); > + > +static inline void > +netdev_devmem_binding_get(struct netdev_dmabuf_binding *binding) > +{ > + refcount_inc(&binding->ref); > +} > + > +static inline void > +netdev_devmem_binding_put(struct netdev_dmabuf_binding *binding) > +{ > + if (!refcount_dec_and_test(&binding->ref)) > + return; > + > + __netdev_devmem_binding_free(binding); > +} Not a big deal, but it looks like reimplemented version of kref_get/kref_put to me. Thanks
