Message-ID: <CAGXJAmz+WPtRjjfXBh94fvpLYDsckAaF0hajcx=u-29gof7ZQg@mail.gmail.com>
Date: Mon, 9 Dec 2024 09:54:26 -0800
From: John Ousterhout <ouster@...stanford.edu>
To: netdev@...r.kernel.org
Subject: Re: [PATCH net-next 01/12] net: homa: define user-visible API for Homa

This patch was sent by mistake; please ignore. Sorry about that...

On Mon, Dec 9, 2024 at 9:52 AM John Ousterhout <ouster@...stanford.edu> wrote:
>
> Note: for man pages, see the Homa Wiki at:
> https://homa-transport.atlassian.net/wiki/spaces/HOMA/overview
>
> Signed-off-by: John Ousterhout <ouster@...stanford.edu>
> ---
>  include/uapi/linux/homa.h | 199 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 199 insertions(+)
>  create mode 100644 include/uapi/linux/homa.h
>
> diff --git a/include/uapi/linux/homa.h b/include/uapi/linux/homa.h
> new file mode 100644
> index 000000000000..306d272e4b63
> --- /dev/null
> +++ b/include/uapi/linux/homa.h
> @@ -0,0 +1,199 @@
> +/* SPDX-License-Identifier: BSD-2-Clause */
> +
> +/* This file defines the kernel call interface for the Homa
> + * transport protocol.
> + */
> +
> +#ifndef _UAPI_LINUX_HOMA_H
> +#define _UAPI_LINUX_HOMA_H
> +
> +#include <linux/types.h>
> +#ifndef __KERNEL__
> +#include <netinet/in.h>
> +#include <sys/socket.h>
> +#endif
> +
> +#ifdef __cplusplus
> +extern "C"
> +{
> +#endif
> +
> +/* IANA-assigned Internet Protocol number for Homa. */
> +#define IPPROTO_HOMA 146
> +
> +/**
> + * define HOMA_MAX_MESSAGE_LENGTH - Maximum bytes of payload in a Homa
> + * request or response message.
> + */
> +#define HOMA_MAX_MESSAGE_LENGTH 1000000
> +
> +/**
> + * define HOMA_BPAGE_SIZE - Number of bytes in pages used for receive
> + * buffers. Must be power of two.
> + */
> +#define HOMA_BPAGE_SHIFT 16
> +#define HOMA_BPAGE_SIZE (1 << HOMA_BPAGE_SHIFT)
> +
> +/**
> + * define HOMA_MAX_BPAGES: The largest number of bpages that will be required
> + * to store an incoming message.
> + */
> +#define HOMA_MAX_BPAGES ((HOMA_MAX_MESSAGE_LENGTH + HOMA_BPAGE_SIZE - 1) \
> +               >> HOMA_BPAGE_SHIFT)
> +
> +/**
> + * define HOMA_MIN_DEFAULT_PORT - The 16-bit port space is divided into
> + * two nonoverlapping regions. Ports 1-32767 are reserved exclusively
> + * for well-defined server ports. The remaining ports are used for client
> + * ports; these are allocated automatically by Homa. Port 0 is reserved.
> + */
> +#define HOMA_MIN_DEFAULT_PORT 0x8000
> +
> +/**
> + * Holds either an IPv4 or IPv6 address (smaller and easier to use than
> + * sockaddr_storage).
> + */
> +union sockaddr_in_union {
> +       struct sockaddr sa;
> +       struct sockaddr_in in4;
> +       struct sockaddr_in6 in6;
> +};
> +
> +/**
> + * struct homa_sendmsg_args - Provides information needed by Homa's
> + * sendmsg; passed to sendmsg using the msg_control field.
> + */
> +struct homa_sendmsg_args {
> +       /**
> +        * @id: (in/out) An initial value of 0 means a new request is
> +        * being sent; nonzero means the message is a reply to the given
> +        * id. If the message is a request, then the value is modified to
> +        * hold the id of the new RPC.
> +        */
> +       uint64_t id;
> +
> +       /**
> +        * @completion_cookie: (in) Used only for request messages; will be
> +        * returned by recvmsg when the RPC completes. Typically used to
> +        * locate app-specific info about the RPC.
> +        */
> +       uint64_t completion_cookie;
> +};
> +
> +#if !defined(__cplusplus)
> +_Static_assert(sizeof(struct homa_sendmsg_args) >= 16,
> +              "homa_sendmsg_args shrunk");
> +_Static_assert(sizeof(struct homa_sendmsg_args) <= 16,
> +              "homa_sendmsg_args grew");
> +#endif
> +
> +/**
> + * struct homa_recvmsg_args - Provides information needed by Homa's
> + * recvmsg; passed to recvmsg using the msg_control field.
> + */
> +struct homa_recvmsg_args {
> +       /**
> +        * @id: (in/out) Initially specifies the id of the desired RPC, or 0
> +        * if any RPC is OK; returns the actual id received.
> +        */
> +       uint64_t id;
> +
> +       /**
> +        * @completion_cookie: (out) If the incoming message is a response,
> +        * this will return the completion cookie specified when the
> +        * request was sent. For requests this will always be zero.
> +        */
> +       uint64_t completion_cookie;
> +
> +       /**
> +        * @flags: (in) OR-ed combination of bits that control the operation.
> +        * See below for values.
> +        */
> +       int flags;
> +
> +       /**
> +        * @error_addr: the address of the peer is stored here when available.
> +        * This field is different from the msg_name field in struct msghdr
> +        * in that the msg_name field isn't set after errors. This field will
> +        * always be set when peer information is available, which includes
> +        * some error cases.
> +        */
> +       union sockaddr_in_union peer_addr;
> +
> +       /**
> +        * @num_bpages: (in/out) Number of valid entries in @bpage_offsets.
> +        * Passes in bpages from previous messages that can now be
> +        * recycled; returns bpages from the new message.
> +        */
> +       uint32_t num_bpages;
> +
> +       uint32_t _pad[1];
> +
> +       /**
> +        * @bpage_offsets: (in/out) Each entry is an offset into the buffer
> +        * region for the socket pool. When returned from recvmsg, the
> +        * offsets indicate where fragments of the new message are stored. All
> +        * entries but the last refer to full buffer pages (HOMA_BPAGE_SIZE bytes)
> +        * and are bpage-aligned. The last entry may refer to a bpage fragment and
> +        * is not necessarily aligned. The application now owns these bpages and
> +        * must eventually return them to Homa, using bpage_offsets in a future
> +        * recvmsg invocation.
> +        */
> +       uint32_t bpage_offsets[HOMA_MAX_BPAGES];
> +};
> +
> +#if !defined(__cplusplus)
> +_Static_assert(sizeof(struct homa_recvmsg_args) >= 120,
> +              "homa_recvmsg_args shrunk");
> +_Static_assert(sizeof(struct homa_recvmsg_args) <= 120,
> +              "homa_recvmsg_args grew");
> +#endif
> +
> +/* Flag bits for homa_recvmsg_args.flags (see man page for documentation):
> + */
> +#define HOMA_RECVMSG_REQUEST       0x01
> +#define HOMA_RECVMSG_RESPONSE      0x02
> +#define HOMA_RECVMSG_NONBLOCKING   0x04
> +#define HOMA_RECVMSG_VALID_FLAGS   0x07
> +
> +/** define SO_HOMA_SET_BUF: setsockopt option for specifying buffer region. */
> +#define SO_HOMA_SET_BUF 10
> +
> +/** struct homa_set_buf - setsockopt argument for SO_HOMA_SET_BUF. */
> +struct homa_set_buf_args {
> +       /** @start: First byte of buffer region. */
> +       void *start;
> +
> +       /** @length: Total number of bytes available at @start. */
> +       size_t length;
> +};
> +
> +/**
> + * Meanings of the bits in Homa's flag word, which can be set using
> + * "sysctl /net/homa/flags".
> + */
> +
> +/**
> + * Disable the output throttling mechanism: always send all packets
> + * immediately.
> + */
> +#define HOMA_FLAG_DONT_THROTTLE   2
> +
> +int     homa_send(int sockfd, const void *message_buf,
> +                 size_t length, const union sockaddr_in_union *dest_addr,
> +                 uint64_t *id, uint64_t completion_cookie);
> +int     homa_sendv(int sockfd, const struct iovec *iov,
> +                  int iovcnt, const union sockaddr_in_union *dest_addr,
> +                  uint64_t *id, uint64_t completion_cookie);
> +ssize_t homa_reply(int sockfd, const void *message_buf,
> +                  size_t length, const union sockaddr_in_union *dest_addr,
> +                  uint64_t id);
> +ssize_t homa_replyv(int sockfd, const struct iovec *iov,
> +                   int iovcnt, const union sockaddr_in_union *dest_addr,
> +                   uint64_t id);
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* _UAPI_LINUX_HOMA_H */
> --
> 2.34.1
>

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