Re: [PATCH net-next v4 09/18] net/smc: introduce SMC-D loopback device

[Wen Gu]

On 2023/9/25 19:50, Alexandra Winter wrote:
> On 24.09.23 17:16, Wen Gu wrote:
> > This patch introduces a kind of loopback device for SMC-D. The device
> > is created when SMC module is loaded and destroyed when the SMC module
> > is unloaded. The loopback device is a kernel device used only by the
> > SMC module and is not restricted by net namespace, so it can be used
> > for local inter-process or inter-container communication.
> >
> > Signed-off-by: Wen Gu <guwen@xxxxxxxxxxxxxxxxx>
> > ---
> >   net/smc/Kconfig        |  13 ++++
> >   net/smc/Makefile       |   2 +-
> >   net/smc/af_smc.c       |  12 +++-
> >   net/smc/smc_loopback.c | 165 +++++++++++++++++++++++++++++++++++++++++++++++++
> >   net/smc/smc_loopback.h |  33 ++++++++++
> >   5 files changed, 223 insertions(+), 2 deletions(-)
> >   create mode 100644 net/smc/smc_loopback.c
> >   create mode 100644 net/smc/smc_loopback.h
>
>
> Hello Wen Gu,
>
> thank you for adding the Kconfig, so the distributions can decide when to offer this feature.
>
> I propose you add some kind of runtime switch as well. Not every user who loads the SMC module
> may want to exploit smcd-loopback. Especially in native environements without containers.
>
> If no RoCE interfaces or no ISM interfaces exist, the respective handling is skipped in SMC.
> If loopback is always created unconditionally, there is no way to opt-out.

Yes, I need to think about this. Make a runtime switch to enable/disable the loopback-ism just
like ip link up/down. An rough idea is to add an smc-tools command, like 'smcd device disable/enable loopback'.

Thank you very much.

Regards,
Wen Gu