On 15/05/2024 13:01, Nikolay Aleksandrov wrote: > 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. > On second thought nevermind this, sorry for the noise. >> + 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 >
