[PATCH net-next 0/2] Introduce IPPROTO_SMC

D. Wythe
2024-05-10T04:12:26Z

From: "D. Wythe" <alibuda@linux.alibaba.com>

This patch allows to create smc socket via AF_INET,
similar to the following code,

/* create v4 smc sock */
v4 = socket(AF_INET, SOCK_STREAM, IPPROTO_SMC);

/* create v6 smc sock */
v6 = socket(AF_INET6, SOCK_STREAM, IPPROTO_SMC);

There are several reasons why we believe it is appropriate here:

1. For smc sockets, it actually use IPv4 (AF-INET) or IPv6 (AF-INET6)
address. There is no AF_SMC address at all.

2. Create smc socket in the AF_INET(6) path, which allows us to reuse
the infrastructure of AF_INET(6) path, such as common ebpf hooks.
Otherwise, smc have to implement it again in AF_SMC path. Such as:
1. Replace IPPROTO_TCP with IPPROTO_SMC in the socket() syscall
initiated by the user, without the use of LD-PRELOAD.
2. Select whether immediate fallback is required based on peer's port/ip
before connect().

A very significant result is that we can now use eBPF to implement smc_run
instead of LD_PRELOAD, who is completely ineffective in scenarios of static
linking.

Another potential value is that we are attempting to optimize the performance of
fallback socks, where merging socks is an important part, and it relies on the
creation of SMC sockets under the AF_INET path. (More information :
https://lore.kernel.org/netdev/1699442703-25015-1-git-send-email-alibuda@linux.alibaba.com/T/)

D. Wythe (2):
net/smc: refatoring initialization of smc sock
net/smc: Introduce IPPROTO_SMC

include/uapi/linux/in.h | 2 +
net/smc/af_smc.c | 222 +++++++++++++++++++++++++++++++++++++++---------
net/smc/inet_smc.h | 32 +++++++
3 files changed, 214 insertions(+), 42 deletions(-)
create mode 100644 net/smc/inet_smc.h

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1.8.3.1