From: David Wei <dw@davidwei.uk>
To: Mina Almasry <almasrymina@google.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, linux-alpha@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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"Andreas Larsson" <andreas@gaisler.com>,
"Jesper Dangaard Brouer" <hawk@kernel.org>,
"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Masami Hiramatsu" <mhiramat@kernel.org>,
"Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>,
"Arnd Bergmann" <arnd@arndb.de>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Martin KaFai Lau" <martin.lau@linux.dev>,
"Eduard Zingerman" <eddyz87@gmail.com>,
"Song Liu" <song@kernel.org>,
"Yonghong Song" <yonghong.song@linux.dev>,
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"KP Singh" <kpsingh@kernel.org>,
"Stanislav Fomichev" <sdf@google.com>,
"Hao Luo" <haoluo@google.com>, "Jiri Olsa" <jolsa@kernel.org>,
"Steffen Klassert" <steffen.klassert@secunet.com>,
"Herbert Xu" <herbert@gondor.apana.org.au>,
"David Ahern" <dsahern@kernel.org>,
"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>,
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"Yunsheng Lin" <linyunsheng@huawei.com>,
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"Harshitha Ramamurthy" <hramamurthy@google.com>,
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"Willem de Bruijn" <willemb@google.com>,
"Kaiyuan Zhang" <kaiyuanz@google.com>
Subject: Re: [PATCH net-next v9 11/14] tcp: RX path for devmem TCP
Date: Wed, 22 May 2024 23:02:54 -0700 [thread overview]
Message-ID: <9097e78d-0e7d-43bd-bafd-e53a4872a4d1@davidwei.uk> (raw)
In-Reply-To: <20240510232128.1105145-12-almasrymina@google.com>
On 2024-05-10 16:21, Mina Almasry wrote:
> +/* On error, returns the -errno. On success, returns number of bytes sent to the
> + * user. May not consume all of @remaining_len.
> + */
> +static int tcp_recvmsg_dmabuf(struct sock *sk, const struct sk_buff *skb,
> + unsigned int offset, struct msghdr *msg,
> + int remaining_len)
> +{
> + struct dmabuf_cmsg dmabuf_cmsg = { 0 };
> + struct tcp_xa_pool tcp_xa_pool;
> + unsigned int start;
> + int i, copy, n;
> + int sent = 0;
> + int err = 0;
> +
> + tcp_xa_pool.max = 0;
> + tcp_xa_pool.idx = 0;
> + do {
> + start = skb_headlen(skb);
> +
> + if (skb_frags_readable(skb)) {
> + err = -ENODEV;
> + goto out;
> + }
> +
> + /* Copy header. */
> + copy = start - offset;
> + if (copy > 0) {
> + copy = min(copy, remaining_len);
> +
> + n = copy_to_iter(skb->data + offset, copy,
> + &msg->msg_iter);
> + if (n != copy) {
> + err = -EFAULT;
> + goto out;
> + }
> +
> + offset += copy;
> + remaining_len -= copy;
> +
> + /* First a dmabuf_cmsg for # bytes copied to user
> + * buffer.
> + */
> + memset(&dmabuf_cmsg, 0, sizeof(dmabuf_cmsg));
> + dmabuf_cmsg.frag_size = copy;
> + err = put_cmsg(msg, SOL_SOCKET, SO_DEVMEM_LINEAR,
> + sizeof(dmabuf_cmsg), &dmabuf_cmsg);
> + if (err || msg->msg_flags & MSG_CTRUNC) {
> + msg->msg_flags &= ~MSG_CTRUNC;
> + if (!err)
> + err = -ETOOSMALL;
> + goto out;
> + }
> +
> + sent += copy;
> +
> + if (remaining_len == 0)
> + goto out;
> + }
> +
> + /* after that, send information of dmabuf pages through a
> + * sequence of cmsg
> + */
> + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
> + skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
> + struct net_iov *niov;
> + u64 frag_offset;
> + int end;
> +
> + /* !skb_frags_readable() should indicate that ALL the
> + * frags in this skb are dmabuf net_iovs. We're checking
> + * for that flag above, but also check individual frags
> + * here. If the tcp stack is not setting
> + * skb_frags_readable() correctly, we still don't want
> + * to crash here.
> + */
> + if (!skb_frag_net_iov(frag)) {
> + net_err_ratelimited("Found non-dmabuf skb with net_iov");
> + err = -ENODEV;
> + goto out;
> + }
> +
> + niov = skb_frag_net_iov(frag);
Sorry if we've already discussed this.
We have this additional hunk:
+ if (niov->pp->mp_ops != &dmabuf_devmem_ops) {
+ err = -ENODEV;
+ goto out;
+ }
In case one of our skbs end up here, skb_frag_is_net_iov() and
!skb_frags_readable(). Does this even matter? And if so then is there a
better way to distinguish between our two types of net_iovs?
next prev parent reply other threads:[~2024-05-23 6:02 UTC|newest]
Thread overview: 28+ 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
2024-05-18 18:46 ` David Wei
2024-05-29 19:49 ` Mina Almasry
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 [this message]
2024-05-28 17:36 ` Mina Almasry
2024-05-29 2:42 ` Pavel Begunkov
2024-05-29 17:20 ` Mina Almasry
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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