[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <8335651b-3296-460a-b9a6-4a36a7ec8bc8@gmail.com>
Date: Tue, 2 Jul 2024 15:51:27 +0100
From: Pavel Begunkov <asml.silence@...il.com>
To: Mina Almasry <almasrymina@...gle.com>, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
linux-alpha@...r.kernel.org, linux-mips@...r.kernel.org,
linux-parisc@...r.kernel.org, sparclinux@...r.kernel.org,
linux-trace-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
bpf@...r.kernel.org, linux-kselftest@...r.kernel.org,
linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org
Cc: "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>, Donald Hunter <donald.hunter@...il.com>,
Jonathan Corbet <corbet@....net>,
Richard Henderson <richard.henderson@...aro.org>,
Ivan Kokshaysky <ink@...assic.park.msu.ru>, Matt Turner
<mattst88@...il.com>, Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
"James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
Helge Deller <deller@....de>, Andreas Larsson <andreas@...sler.com>,
Jesper Dangaard Brouer <hawk@...nel.org>,
Ilias Apalodimas <ilias.apalodimas@...aro.org>,
Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu
<mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Arnd Bergmann <arnd@...db.de>, Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <martin.lau@...ux.dev>, Eduard Zingerman
<eddyz87@...il.com>, Song Liu <song@...nel.org>,
Yonghong Song <yonghong.song@...ux.dev>,
John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>,
Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>,
Jiri Olsa <jolsa@...nel.org>, Steffen Klassert
<steffen.klassert@...unet.com>, Herbert Xu <herbert@...dor.apana.org.au>,
David Ahern <dsahern@...nel.org>,
Willem de Bruijn <willemdebruijn.kernel@...il.com>,
Shuah Khan <shuah@...nel.org>, Sumit Semwal <sumit.semwal@...aro.org>,
Christian König <christian.koenig@....com>,
Bagas Sanjaya <bagasdotme@...il.com>, Christoph Hellwig <hch@...radead.org>,
Nikolay Aleksandrov <razor@...ckwall.org>, David Wei <dw@...idwei.uk>,
Jason Gunthorpe <jgg@...pe.ca>, Yunsheng Lin <linyunsheng@...wei.com>,
Shailend Chand <shailend@...gle.com>,
Harshitha Ramamurthy <hramamurthy@...gle.com>,
Shakeel Butt <shakeel.butt@...ux.dev>, Jeroen de Borst
<jeroendb@...gle.com>, Praveen Kaligineedi <pkaligineedi@...gle.com>,
Willem de Bruijn <willemb@...gle.com>, Kaiyuan Zhang <kaiyuanz@...gle.com>
Subject: Re: [PATCH net-next v15 10/14] tcp: RX path for devmem TCP
On 6/28/24 01:32, 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_frags, 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.
Already gave it in v13, but it got lost
Reviewed-by: Pavel Begunkov <asml.silence@...il.com>
--
Pavel Begunkov
Powered by blists - more mailing lists