On 11/05/2024 02:21, 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, but the binding doesn't take effect until > the driver actually reconfigures its queues, and re-initializes its page > pool. > > The netdev_dmabuf_binding struct is refcounted, and releases its > resources only when all the refs are released. > > Signed-off-by: Willem de Bruijn <willemb@xxxxxxxxxx> > Signed-off-by: Kaiyuan Zhang <kaiyuanz@xxxxxxxxxx> > Signed-off-by: Mina Almasry <almasrymina@xxxxxxxxxx> > > --- > > v9: https://lore.kernel.org/all/20240403002053.2376017-5-almasrymina@xxxxxxxxxx/ > - Removed net_devmem_restart_rx_queues and put it in its own patch > (David). > > v8: > - move dmabuf_devmem_ops usage to later patch to avoid patch-by-patch > build error. > > v7: > - Use IS_ERR() instead of IS_ERR_OR_NULL() for the dma_buf_get() return > value. > - Changes netdev_* naming in devmem.c to net_devmem_* (Yunsheng). > - DMA_BIDIRECTIONAL -> DMA_FROM_DEVICE (Yunsheng). > - Added a comment around recovering of the old rx queue in > net_devmem_restart_rx_queue(), and added freeing of old_mem if the > restart of the old queue fails. (Yunsheng). > - Use kernel-family sock-priv (Jakub). > - Put pp_memory_provider_params in netdev_rx_queue instead of the > dma-buf specific binding (Pavel & David). > - Move queue management ops to queue_mgmt_ops instead of netdev_ops > (Jakub). > - Remove excess whitespaces (Jakub). > - Use genlmsg_iput (Jakub). > > v6: > - Validate rx queue index > - Refactor new functions into devmem.c (Pavel) > > v5: > - Renamed page_pool_iov to net_iov, and moved that support to devmem.h > or netmem.h. > > v1: > - Introduce devmem.h instead of bloating netdevice.h (Jakub) > - ENOTSUPP -> EOPNOTSUPP (checkpatch.pl I think) > - Remove unneeded rcu protection for binding->list (rtnl protected) > - Removed extraneous err_binding_put: label. > - Removed dma_addr += len (Paolo). > - Don't override err on netdev_bind_dmabuf_to_queue failure. > - Rename devmem -> dmabuf (David). > - Add id to dmabuf binding (David/Stan). > - Fix missing xa_destroy bound_rq_list. > - Use queue api to reset bound RX queues (Jakub). > - Update netlink API for rx-queue type (tx/re) (Jakub). > > RFC v3: > - Support multi rx-queue binding > > --- > Documentation/netlink/specs/netdev.yaml | 4 + > include/net/devmem.h | 111 +++++++++++ > include/net/netdev_rx_queue.h | 2 + > include/net/netmem.h | 10 + > include/net/page_pool/types.h | 5 + > net/core/Makefile | 2 +- > net/core/dev.c | 3 + > net/core/devmem.c | 254 ++++++++++++++++++++++++ > net/core/netdev-genl-gen.c | 4 + > net/core/netdev-genl-gen.h | 4 + > net/core/netdev-genl.c | 105 +++++++++- > 11 files changed, 501 insertions(+), 3 deletions(-) > create mode 100644 include/net/devmem.h > create mode 100644 net/core/devmem.c > [snip] > +/* Protected by rtnl_lock() */ > +static DEFINE_XARRAY_FLAGS(net_devmem_dmabuf_bindings, XA_FLAGS_ALLOC1); > + > +void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding) > +{ > + struct netdev_rx_queue *rxq; > + unsigned long xa_idx; > + unsigned int rxq_idx; > + > + if (!binding) > + return; > + > + if (binding->list.next) > + list_del(&binding->list); > + minor nit: In theory list.next can still be != null if it's poisoned (e.g. after del). You can use the list api here (!list_empty(&binding->list) -> list_del_init(&binding->list)) if you initialize it in net_devmem_bind_dmabuf(), then you'll also get nice list debugging. > + xa_for_each(&binding->bound_rxq_list, xa_idx, rxq) { > + if (rxq->mp_params.mp_priv == binding) { > + /* We hold the rtnl_lock while binding/unbinding > + * dma-buf, so we can't race with another thread that > + * is also modifying this value. However, the page_pool > + * may read this config while it's creating its > + * rx-queues. WRITE_ONCE() here to match the > + * READ_ONCE() in the page_pool. > + */ > + WRITE_ONCE(rxq->mp_params.mp_ops, NULL); > + WRITE_ONCE(rxq->mp_params.mp_priv, NULL); > + > + rxq_idx = get_netdev_rx_queue_index(rxq); > + > + netdev_rx_queue_restart(binding->dev, rxq_idx); > + } > + } > + > + xa_erase(&net_devmem_dmabuf_bindings, binding->id); > + > + net_devmem_dmabuf_binding_put(binding); > +} [snip] Cheers, Nik
