From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp1.cs.Stanford.EDU (smtp1.cs.stanford.edu [171.64.64.25]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 52E053859E1 for ; Fri, 10 Apr 2026 20:03:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=171.64.64.25 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775851408; cv=none; b=KtIbXLzvvkq62qpCH+quR89MSVHtCl0StWFuw9aa8zfup2yVVY+TBeOm5WEywRwqVwNycdstdta5XPX86CLZRybD5CQJ3po1/ooKp4tZVofs1xigWztxBfZ2yy5hhRBq0vONlg22/nY2tj6ieEwncET8g5AEzbMPf+m1r3Rv/SA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775851408; c=relaxed/simple; bh=ZYEu8fJisf1XFxOvWPeNznX3QHzg8EUuyAoFoTUAwUM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uEgUo/sl76+Fq8Hc+ogeoIMXNnJ8krchNC4FeTmMDuIy6rSU5HRkzQDF16VvTzFF+LUYNUzSg088JX/llhUoZsPyUlgy2IS7BEp43K/M0HAIDc+w3yZScBbDj4HWrKES8JzKzbHWmVeV7dKIED4mPcQvIXJjxE+alV08cUKH0Y8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=cs.stanford.edu; spf=pass smtp.mailfrom=cs.stanford.edu; dkim=pass (2048-bit key) header.d=cs.stanford.edu header.i=@cs.stanford.edu header.b=Q2KopwTp; arc=none smtp.client-ip=171.64.64.25 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=cs.stanford.edu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=cs.stanford.edu Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=cs.stanford.edu header.i=@cs.stanford.edu header.b="Q2KopwTp" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=cs.stanford.edu; s=cs2308; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=YzbvX2DNtdET8j8+8x0Hcoh6CcNV+x6PGyfyr7QmRgs=; t=1775851406; x=1776715406; b=Q2KopwTpBWhlIwa4TXT85T/WG8KBp9B/r59AQ7rRTXTM5Ti4E/9qii6vcNLCrIxPvwtdYfoCZPL Ikpx1iCKskiEEmuehWJvVckWmrciDU1XpvcytTvzpMXHhD33QC6IKi2CZuQUG7xNXe27TCQ8Llcg4 THkvgGj7NXaHIbbLYp9UJ027DAloX9tSocFDuoplavoA2E5b0Avs+anI8kjyiJQffI2UNJugLWhqL +HRR0pN9bP0wM+rKruLFuFoO1ZnbbTE6ELbBUNOZ4F3rvu+rLsLLnj7W6a65z43B5i6XFXdl/sqrK 11FuEbe8H9Qthhn6dNwZUKAOjOwPxvOYpPwg==; Received: from ouster448.stanford.edu ([172.24.72.71]:51553 helo=ouster2022) by smtp1.cs.Stanford.EDU with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1wBI4U-0003MV-Fu; Fri, 10 Apr 2026 13:03:19 -0700 From: John Ousterhout To: netdev@vger.kernel.org Cc: pabeni@redhat.com, edumazet@google.com, horms@kernel.org, kuba@kernel.org, John Ousterhout Subject: [PATCH net-next v18 01/15] net: homa: define user-visible API for Homa Date: Fri, 10 Apr 2026 13:02:55 -0700 Message-ID: <20260410200310.1915-2-ouster@cs.stanford.edu> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260410200310.1915-1-ouster@cs.stanford.edu> References: <20260410200310.1915-1-ouster@cs.stanford.edu> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Score: -101.0 X-Scan-Signature: 83f7980b8b00ab3607c6aa853105b20e Note: for man pages, see the Homa Wiki at: https://homa-transport.atlassian.net/wiki/spaces/HOMA/overview Signed-off-by: John Ousterhout --- Changes for v18: * Fix types to conform to Linux standards (e.g. __u64 instead of size_t) Changes for v16: * Implement HOMAIOCINFO ioctl. Changes for v14: * Add "WITH Linux-syscall-note" SPDX license note Changes for v11: * Add explicit padding to struct homa_recvmsg_args to fix problems compiling on 32-bit machines. Changes for v9: * Eliminate use of _Static_assert * Remove declarations related to now-defunct homa_api.c Changes for v7: * Add HOMA_SENDMSG_NONBLOCKING flag for sendmsg * API changes for new mechanism for waiting for incoming messages * Add setsockopt SO_HOMA_SERVER (enable incoming requests) * Use u64 and __u64 properly --- MAINTAINERS | 7 + include/uapi/linux/homa.h | 300 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 307 insertions(+) create mode 100644 include/uapi/linux/homa.h diff --git a/MAINTAINERS b/MAINTAINERS index c583c5478ef6..a6e831c2577b 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -11666,6 +11666,13 @@ F: lib/test_hmm* F: mm/hmm* F: tools/testing/selftests/mm/*hmm* +HOMA TRANSPORT PROTOCOL +M: John Ousterhout +S: Maintained +W: https://homa-transport.atlassian.net/wiki/spaces/HOMA +F: include/uapi/linux/homa.h +F: net/homa/ + HONEYWELL ABP2030PA PRESSURE SENSOR SERIES IIO DRIVER M: Petre Rodan L: linux-iio@vger.kernel.org diff --git a/include/uapi/linux/homa.h b/include/uapi/linux/homa.h new file mode 100644 index 000000000000..e5347e4abe44 --- /dev/null +++ b/include/uapi/linux/homa.h @@ -0,0 +1,300 @@ +/* SPDX-License-Identifier: BSD-2-Clause or GPL-2.0+ WITH Linux-syscall-note */ + +/* This file defines the kernel call interface for the Homa + * transport protocol. + */ + +#ifndef _UAPI_LINUX_HOMA_H +#define _UAPI_LINUX_HOMA_H + +#include +#include +#include +#include + +/* 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_SIZE (1 << HOMA_BPAGE_SHIFT) +#define HOMA_BPAGE_SHIFT 16 + +/** + * 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 + +/** + * 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. + */ + __u64 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. + */ + __u64 completion_cookie; + + /** + * @flags: (in) OR-ed combination of bits that control the operation. + * See below for values. + */ + __u32 flags; + + /** @reserved: Not currently used, must be 0. */ + __u32 reserved; +}; + +/* Flag bits for homa_sendmsg_args.flags (see man page for documentation): + */ +#define HOMA_SENDMSG_PRIVATE 0x01 +#define HOMA_SENDMSG_VALID_FLAGS 0x01 + +/** + * 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) Initial value is 0 to wait for any shared RPC; + * nonzero means wait for that specific (private) RPC. Returns + * the id of the RPC received. + */ + __u64 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. + */ + __u64 completion_cookie; + + /** + * @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. + */ + __u32 num_bpages; + + /** @reserved: Not currently used, must be 0. */ + __u32 reserved; + + /** + * @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. + */ + __u32 bpage_offsets[HOMA_MAX_BPAGES]; +}; + +/** define SO_HOMA_RCVBUF: setsockopt option for specifying buffer region. */ +#define SO_HOMA_RCVBUF 10 + +/** + * define SO_HOMA_SERVER: setsockopt option for specifying whether a + * socket will act as server. + */ +#define SO_HOMA_SERVER 11 + +/** struct homa_rcvbuf_args - setsockopt argument for SO_HOMA_RCVBUF. */ +struct homa_rcvbuf_args { + /** @start: Address of first byte of buffer region in user space. */ + __u64 start; + + /** @length: Total number of bytes available at @start. */ + __u64 length; +}; + +/* Meanings of the bits in Homa's flag word, which can be set using + * "sysctl /net/homa/flags". + */ + +/** + * define HOMA_FLAG_DONT_THROTTLE - disable the output throttling mechanism + * (always send all packets immediately). + */ +#define HOMA_FLAG_DONT_THROTTLE 2 + +/** + * struct homa_rpc_info - Used by HOMAIOCINFO to return information about + * a specific RPC. + */ +struct homa_rpc_info { + /** + * @id: Identifier for the RPC, unique among all RPCs sent by the + * client node. If the low-order bit is 1, this node is the server + * for the RPC; 0 means we are the client. + */ + __u64 id; + + /** @peer: Address of the peer socket for this RPC. */ + union { + struct __kernel_sockaddr_storage storage; + struct sockaddr_in in4; + struct sockaddr_in6 in6; + } peer; + + /** + * @completion_cookie: For client-side RPCs this gives the completion + * cookie specified when the RPC was initiated. For server-side RPCs + * this is zero. + */ + __u64 completion_cookie; + + /** + * @tx_length: Length of the outgoing message in bytes, or -1 if + * the sendmsg hasn't yet been called. + */ + __s32 tx_length; + + /** + * @tx_sent: Number of bytes of the outgoing message that have been + * transmitted at least once. + */ + __u32 tx_sent; + + /** + * @tx_granted: Number of bytes of the outgoing message that the + * receiver has authorized us to transmit (includes unscheduled + * bytes). + */ + __u32 tx_granted; + + /** @reserved: Reserved for future use. */ + __u32 reserved; + + /** + * @rx_length: Length of the incoming message, in bytes. -1 means + * the length is not yet known (this is a client-side RPC and + * no packets have been received). + */ + __s32 rx_length; + + /** + * @rx_remaining: Number of bytes in the incoming message that have + * not yet been received. + */ + __u32 rx_remaining; + + /** + * @rx_gaps: The number of gaps in the incoming message. A gap is + * a range of bytes that have not been received yet, but bytes after + * the gap have been received. + */ + __u32 rx_gaps; + + /** + * @rx_gap_bytes: The total number of bytes in gaps in the incoming + * message. + */ + __u32 rx_gap_bytes; + + /** + * @rx_granted: The number of bytes in the message that the sender + * is authorized to transmit (includes unscheduled bytes). + */ + __u32 rx_granted; + + /** + * @flags: Various single-bit values associated with the RPC: + * HOMA_RPC_BUF_STALL: The incoming message is currently stalled + * because there is insufficient receiver buffer + * space. + * HOMA_RPC_PRIVATE: The RPC has been created as "private"; set + * only on the client side. + * HOMA_RPC_RX_READY: The incoming message is complete and has + * been queued waiting for a thread to call + * recvmsg. + * HOMA_RPC_RX_COPY: There are packets that have been received, + * whose data has not yet been copied from + * packet buffers to user space. + */ + __u16 flags; +#define HOMA_RPC_BUF_STALL 1 +#define HOMA_RPC_PRIVATE 2 +#define HOMA_RPC_RX_READY 4 +#define HOMA_RPC_RX_COPY 8 +}; + +/** + * struct homa_info - In/out argument passed to HOMAIOCINFO. Fields labeled + * as "in" must be set by the application; other fields are returned to the + * application from the kernel. + */ +struct homa_info { + /** + * @rpc_info: (in) Address of memory region in which to store + * information about individual RPCs. Actual type is + * "struct homa_rpc_info *". + */ + __u64 rpc_info; + + /** + * @rpc_info_length: (in) Number of bytes of storage available at + * rpc_info. + */ + __u64 rpc_info_length; + + /** + * @bpool_avail_bytes: Number of bytes in the buffer pool for incoming + * messages that is currently available for new messages. + */ + __u64 bpool_avail_bytes; + + /** @port: Port number handled by this socket. */ + __u32 port; + + /** + * @num_rpcs: Total number of active RPCs (both server and client) for + * this socket. The number stored at @rpc_info will be less than this + * if @rpc_info_length is too small. + */ + __u32 num_rpcs; + + /** + * @error_msg: Provides additional information about the last error + * returned by a Homa-related kernel call such as sendmsg, recvmsg, + * or ioctl. Not updated for some obvious return values such as EINTR + * or EWOULDBLOCK. + */ +#define HOMA_ERROR_MSG_SIZE 100 + char error_msg[HOMA_ERROR_MSG_SIZE]; +}; + +/* I/O control calls on Homa sockets.*/ +#define HOMAIOCINFO _IOWR('h', 1, struct homa_info) + +#endif /* _UAPI_LINUX_HOMA_H */ -- 2.43.0