From: Nikolay Aleksandrov <razor@blackwall.org>
To: Mina Almasry <almasrymina@google.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
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Cc: "Donald Hunter" <donald.hunter@gmail.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
"Eric Dumazet" <edumazet@google.com>,
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"Yonghong Song" <yonghong.song@linux.dev>,
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"Herbert Xu" <herbert@gondor.apana.org.au>,
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"Willem de Bruijn" <willemdebruijn.kernel@gmail.com>,
"Shuah Khan" <shuah@kernel.org>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
"Christian König" <christian.koenig@amd.com>,
"Pavel Begunkov" <asml.silence@gmail.com>,
"David Wei" <dw@davidwei.uk>, "Jason Gunthorpe" <jgg@ziepe.ca>,
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"Shailend Chand" <shailend@google.com>,
"Harshitha Ramamurthy" <hramamurthy@google.com>,
"Shakeel Butt" <shakeel.butt@linux.dev>,
"Jeroen de Borst" <jeroendb@google.com>,
"Praveen Kaligineedi" <pkaligineedi@google.com>,
"Willem de Bruijn" <willemb@google.com>,
"Kaiyuan Zhang" <kaiyuanz@google.com>
Subject: Re: [PATCH net-next v9 04/14] netdev: support binding dma-buf to netdevice
Date: Wed, 15 May 2024 13:19:47 +0300 [thread overview]
Message-ID: <f9a8f912-5cb7-4184-be2d-187052c04e2e@blackwall.org> (raw)
In-Reply-To: <59b1ec87-03dc-4336-8ce1-cb97e5abb7d6@blackwall.org>
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@google.com>
>> Signed-off-by: Kaiyuan Zhang <kaiyuanz@google.com>
>> Signed-off-by: Mina Almasry <almasrymina@google.com>
>>
>> ---
>>
>> v9: https://lore.kernel.org/all/20240403002053.2376017-5-almasrymina@google.com/
>> - 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
>
next prev parent reply other threads:[~2024-05-15 10:19 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-10 23:21 [PATCH net-next v9 00/14] Device Memory TCP Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 01/14] netdev: add netdev_rx_queue_restart() Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 02/14] net: page_pool: create hooks for custom page providers Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 03/14] net: netdev netlink api to bind dma-buf to a net device Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 04/14] netdev: support binding dma-buf to netdevice Mina Almasry
2024-05-15 10:01 ` Nikolay Aleksandrov
2024-05-15 10:19 ` Nikolay Aleksandrov [this message]
2024-05-18 18:46 ` David Wei
2024-05-18 18:57 ` David Wei
2024-05-10 23:21 ` [PATCH net-next v9 05/14] netdev: netdevice devmem allocator Mina Almasry
2024-05-18 0:39 ` David Wei
2024-05-10 23:21 ` [PATCH net-next v9 06/14] page_pool: convert to use netmem Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 07/14] page_pool: devmem support Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 08/14] memory-provider: dmabuf devmem memory provider Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 09/14] net: support non paged skb frags Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 10/14] net: add support for skbs with unreadable frags Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 11/14] tcp: RX path for devmem TCP Mina Almasry
2024-05-23 6:02 ` David Wei
2024-05-28 17:36 ` Mina Almasry
2024-05-29 2:42 ` Pavel Begunkov
2024-05-10 23:21 ` [PATCH net-next v9 12/14] net: add SO_DEVMEM_DONTNEED setsockopt to release RX frags Mina Almasry
2024-05-15 9:52 ` Nikolay Aleksandrov
2024-05-10 23:21 ` [PATCH net-next v9 13/14] net: add devmem TCP documentation Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 14/14] selftests: add ncdevmem, netcat for devmem TCP Mina Almasry
2024-05-13 23:31 ` [PATCH net-next v9 00/14] Device Memory TCP Jakub Kicinski
2024-05-14 17:15 ` Mina Almasry
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