From: David Ahern <dsahern@kernel.org>
To: Mina Almasry <almasrymina@google.com>,
Shailend Chand <shailend@google.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, linux-arch@vger.kernel.org,
linux-kselftest@vger.kernel.org, bpf@vger.kernel.org,
linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org
Cc: "David S. Miller" <davem@davemloft.net>,
"Eric Dumazet" <edumazet@google.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Paolo Abeni" <pabeni@redhat.com>,
"Jonathan Corbet" <corbet@lwn.net>,
"Jeroen de Borst" <jeroendb@google.com>,
"Praveen Kaligineedi" <pkaligineedi@google.com>,
"Jesper Dangaard Brouer" <hawk@kernel.org>,
"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
"Arnd Bergmann" <arnd@arndb.de>,
"Willem de Bruijn" <willemdebruijn.kernel@gmail.com>,
"Shuah Khan" <shuah@kernel.org>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
"Christian König" <christian.koenig@amd.com>,
"Yunsheng Lin" <linyunsheng@huawei.com>,
"Harshitha Ramamurthy" <hramamurthy@google.com>,
"Shakeel Butt" <shakeelb@google.com>,
"Willem de Bruijn" <willemb@google.com>,
"Kaiyuan Zhang" <kaiyuanz@google.com>
Subject: Re: [net-next v1 13/16] tcp: RX path for devmem TCP
Date: Fri, 8 Dec 2023 10:55:04 -0700 [thread overview]
Message-ID: <dd47a2a4-cb80-4164-8855-045999931a8e@kernel.org> (raw)
In-Reply-To: <20231208005250.2910004-14-almasrymina@google.com>
On 12/7/23 5:52 PM, Mina Almasry wrote:
> In tcp_recvmsg_locked(), detect if the skb being received by the user
> is a devmem skb. In this case - if the user provided the MSG_SOCK_DEVMEM
> flag - pass it to tcp_recvmsg_devmem() for custom handling.
>
> tcp_recvmsg_devmem() copies any data in the skb header to the linear
> buffer, and returns a cmsg to the user indicating the number of bytes
> returned in the linear buffer.
>
> tcp_recvmsg_devmem() then loops over the unaccessible devmem skb frags,
> and returns to the user a cmsg_devmem indicating the location of the
> data in the dmabuf device memory. cmsg_devmem contains this information:
>
> 1. the offset into the dmabuf where the payload starts. 'frag_offset'.
> 2. the size of the frag. 'frag_size'.
> 3. an opaque token 'frag_token' to return to the kernel when the buffer
> is to be released.
>
> The pages awaiting freeing are stored in the newly added
> sk->sk_user_pages, and each page passed to userspace is get_page()'d.
> This reference is dropped once the userspace indicates that it is
> done reading this page. All pages are released when the socket is
> destroyed.
>
> 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>
>
> ---
>
> Changes in v1:
> - Added dmabuf_id to dmabuf_cmsg (David/Stan).
> - Devmem -> dmabuf (David).
> - Change tcp_recvmsg_dmabuf() check to skb->dmabuf (Paolo).
> - Use __skb_frag_ref() & napi_pp_put_page() for refcounting (Yunsheng).
>
> RFC v3:
> - Fixed issue with put_cmsg() failing silently.
>
What happens if a retransmitted packet is received or an rx window is
closed and a probe is received where the kernel drops the skb - is the
iov reference(s) in the skb returned to the pool by the stack and ready
for use again?
next prev parent reply other threads:[~2023-12-08 17:55 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-08 0:52 [net-next v1 00/16] Device Memory TCP Mina Almasry
2023-12-08 0:52 ` [net-next v1 01/16] net: page_pool: factor out releasing DMA from releasing the page Mina Almasry
2023-12-10 3:49 ` Shakeel Butt
2023-12-12 8:11 ` Ilias Apalodimas
2023-12-08 0:52 ` [net-next v1 02/16] net: page_pool: create hooks for custom page providers Mina Almasry
2023-12-12 8:07 ` Ilias Apalodimas
2023-12-12 14:47 ` Mina Almasry
2023-12-08 0:52 ` [net-next v1 03/16] queue_api: define queue api Mina Almasry
2023-12-14 1:15 ` Jakub Kicinski
2023-12-08 0:52 ` [net-next v1 04/16] gve: implement " Mina Almasry
2024-03-05 11:45 ` Arnd Bergmann
2023-12-08 0:52 ` [net-next v1 05/16] net: netdev netlink api to bind dma-buf to a net device Mina Almasry
2023-12-14 1:17 ` Jakub Kicinski
2023-12-08 0:52 ` [net-next v1 06/16] netdev: support binding dma-buf to netdevice Mina Almasry
2023-12-08 15:40 ` kernel test robot
2023-12-08 16:02 ` kernel test robot
2023-12-08 17:48 ` David Ahern
2023-12-08 19:22 ` Mina Almasry
2023-12-08 20:32 ` Mina Almasry
2023-12-09 23:29 ` David Ahern
2023-12-11 2:19 ` Mina Almasry
2023-12-08 0:52 ` [net-next v1 07/16] netdev: netdevice devmem allocator Mina Almasry
2023-12-08 17:56 ` David Ahern
2023-12-08 19:27 ` Mina Almasry
2023-12-08 0:52 ` [net-next v1 08/16] memory-provider: dmabuf devmem memory provider Mina Almasry
2023-12-08 22:48 ` Pavel Begunkov
2023-12-08 23:25 ` Mina Almasry
2023-12-10 3:03 ` Pavel Begunkov
2023-12-11 2:30 ` Mina Almasry
2023-12-11 20:35 ` Pavel Begunkov
2023-12-14 20:03 ` Mina Almasry
2023-12-19 23:55 ` Pavel Begunkov
2023-12-08 23:05 ` Pavel Begunkov
2023-12-12 12:25 ` Jason Gunthorpe
2023-12-12 13:07 ` Christoph Hellwig
2023-12-12 14:26 ` Mina Almasry
2023-12-12 14:39 ` Jason Gunthorpe
2023-12-12 14:58 ` Mina Almasry
2023-12-12 15:08 ` Jason Gunthorpe
2023-12-13 1:09 ` Mina Almasry
2023-12-13 2:19 ` David Ahern
2023-12-13 7:49 ` Yinjun Zhang
2023-12-08 0:52 ` [net-next v1 09/16] page_pool: device memory support Mina Almasry
2023-12-08 9:30 ` Yunsheng Lin
2023-12-08 16:05 ` Mina Almasry
2023-12-11 2:04 ` Yunsheng Lin
2023-12-11 2:26 ` Mina Almasry
2023-12-11 4:04 ` Mina Almasry
2023-12-11 11:51 ` Yunsheng Lin
2023-12-11 18:14 ` Mina Almasry
2023-12-12 11:17 ` Yunsheng Lin
2023-12-12 14:28 ` Mina Almasry
2023-12-13 11:48 ` Yunsheng Lin
2023-12-13 7:52 ` Mina Almasry
2023-12-08 0:52 ` [net-next v1 10/16] page_pool: don't release iov on elevanted refcount Mina Almasry
2023-12-08 0:52 ` [net-next v1 11/16] net: support non paged skb frags Mina Almasry
2023-12-08 0:52 ` [net-next v1 12/16] net: add support for skbs with unreadable frags Mina Almasry
2023-12-08 0:52 ` [net-next v1 13/16] tcp: RX path for devmem TCP Mina Almasry
2023-12-08 15:40 ` kernel test robot
2023-12-08 17:55 ` David Ahern [this message]
2023-12-08 19:23 ` Mina Almasry
2023-12-08 0:52 ` [net-next v1 14/16] net: add SO_DEVMEM_DONTNEED setsockopt to release RX frags Mina Almasry
2023-12-12 19:08 ` Simon Horman
2023-12-08 0:52 ` [net-next v1 15/16] net: add devmem TCP documentation Mina Almasry
2023-12-12 19:14 ` Simon Horman
2023-12-08 0:52 ` [net-next v1 16/16] selftests: add ncdevmem, netcat for devmem TCP Mina Almasry
2023-12-08 1:47 ` [net-next v1 00/16] Device Memory TCP Mina Almasry
2023-12-08 17:57 ` David Ahern
2023-12-08 19:31 ` Mina Almasry
2023-12-10 3:48 ` Shakeel Butt
2023-12-12 5:58 ` Christoph Hellwig
2023-12-14 6:20 ` patchwork-bot+netdevbpf
2023-12-14 6:48 ` Christoph Hellwig
2023-12-14 6:51 ` Mina Almasry
2023-12-14 6:59 ` Christoph Hellwig
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