netdev - Re: [RFC bpf-next v2 7/8] bpf: add documentation for eBPF helpers (51-57)

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Date:   Tue, 10 Apr 2018 10:50:16 -0700
From:   Andrey Ignatov <rdna@...com>
To:     Quentin Monnet <quentin.monnet@...ronome.com>
CC:     <daniel@...earbox.net>, <ast@...nel.org>, <netdev@...r.kernel.org>,
        <oss-drivers@...ronome.com>, <linux-doc@...r.kernel.org>,
        <linux-man@...r.kernel.org>, Lawrence Brakmo <brakmo@...com>,
        Yonghong Song <yhs@...com>, Josef Bacik <jbacik@...com>
Subject: Re: [RFC bpf-next v2 7/8] bpf: add documentation for eBPF helpers
 (51-57)

Quentin Monnet <quentin.monnet@...ronome.com> [Tue, 2018-04-10 07:43 -0700]:
> + * int bpf_bind(struct bpf_sock_addr_kern *ctx, struct sockaddr *addr, int addr_len)
> + * 	Description
> + * 		Bind the socket associated to *ctx* to the address pointed by
> + * 		*addr*, of length *addr_len*. This allows for making outgoing
> + * 		connection from the desired IP address, which can be useful for
> + * 		example when all processes inside a cgroup should use one
> + * 		single IP address on a host that has multiple IP configured.
> + *
> + * 		This helper works for IPv4 and IPv6, TCP and UDP sockets. The
> + * 		domain (*addr*\ **->sa_family**) must be **AF_INET** (or
> + * 		**AF_INET6**). Looking for a free port to bind to can be
> + * 		expensive, therefore binding to port is not permitted by the
> + * 		helper: *addr*\ **->sin_port** (or **sin6_port**, respectively)
> + * 		must be set to zero.
> + *
> + * 		As for the remote end, both parts of it can be overridden,
> + * 		remote IP and remote port. This can be useful if an application
> + * 		inside a cgroup wants to connect to another application inside
> + * 		the same cgroup or to itself, but knows nothing about the IP
> + * 		address assigned to the cgroup.

The last paragraph ("As for the remote end ...") is not relevant to
bpf_bind() and should be removed. It's about sys_connect hook itself
that can call to bpf_bind() but also has other functionality (and that
other functionality is described by this paragraph).


-- 
Andrey Ignatov