89d69c5d0f
Cong Wang says: ==================== From: Cong Wang <cong.wang@bytedance.com> We have thousands of services connected to a daemon on every host via AF_UNIX dgram sockets, after they are moved into VM, we have to add a proxy to forward these communications from VM to host, because rewriting thousands of them is not practical. This proxy uses an AF_UNIX socket connected to services and a UDP socket to connect to the host. It is inefficient because data is copied between kernel space and user space twice, and we can not use splice() which only supports TCP. Therefore, we want to use sockmap to do the splicing without going to user-space at all (after the initial setup). Currently sockmap only fully supports TCP, UDP is partially supported as it is only allowed to add into sockmap. This patchset, as the second part of the original large patchset, extends sockmap with: 1) cross-protocol support with BPF_SK_SKB_VERDICT; 2) full UDP support. On the high level, ->read_sock() is required for each protocol to support sockmap redirection, and in order to do sock proto update, a new ops ->psock_update_sk_prot() is introduced, which is also required. And the BPF ->recvmsg() is also needed to replace the original ->recvmsg() to retrieve skmsg. To make life easier, we have to get rid of lock_sock() in sk_psock_handle_skb(), otherwise we would have to implement ->sendmsg_locked() on top of ->sendmsg(), which is ugly. Please see each patch for more details. To see the big picture, the original patchset is available here: https://github.com/congwang/linux/tree/sockmap this patchset is also available: https://github.com/congwang/linux/tree/sockmap2 --- v8: get rid of 'offset' in udp_read_sock() add checks for skb_verdict/stream_verdict conflict add two cleanup patches for sock_map_link() add a new test case v7: use work_mutex to protect psock->work return err in udp_read_sock() add patch 6/13 clean up test case v6: get rid of sk_psock_zap_ingress() add rcu work patch v5: use INDIRECT_CALL_2() for function pointers use ingress_lock to fix a race condition found by Jacub rename two helper functions v4: get rid of lock_sock() in sk_psock_handle_skb() get rid of udp_sendmsg_locked() remove an empty line update cover letter v3: export tcp/udp_update_proto() rename sk->sk_prot->psock_update_sk_prot() improve changelogs v2: separate from the original large patchset rebase to the latest bpf-next split UDP test case move inet_csk_has_ulp() check to tcp_bpf.c clean up udp_read_sock() ==================== Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.