Re: [PATCH rdma/wip/jgg-for-next] RDMA/netlink: Hide unimplemented NLDEV commands

[Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

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On Tue, Jan 30, 2018 at 09:03:37AM -0700, Jason Gunthorpe wrote:
> On Tue, Jan 30, 2018 at 04:57:06PM +0100, Jiri Pirko wrote:
> > Tue, Jan 30, 2018 at 04:07:16PM CET, leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org wrote:
> > >From: Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> > >
> > >The nldev was implemented by following devlink implementation,
> > >including SET/DEL/NEW commands. However these commands were not
> > >implemented and hence don't need to be exposed.
> > >
> > >Signed-off-by: Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> > > include/uapi/rdma/rdma_netlink.h | 14 ++++++--------
> > > 1 file changed, 6 insertions(+), 8 deletions(-)
> > >
> > >diff --git a/include/uapi/rdma/rdma_netlink.h b/include/uapi/rdma/rdma_netlink.h
> > >index 17e59bec169e..4c77e2a7b07e 100644
> > >+++ b/include/uapi/rdma/rdma_netlink.h
> > >@@ -227,16 +227,14 @@ enum rdma_nldev_command {
> > > 	RDMA_NLDEV_CMD_UNSPEC,
> > >
> > > 	RDMA_NLDEV_CMD_GET, /* can dump */
> > >-	RDMA_NLDEV_CMD_SET,
> > >-	RDMA_NLDEV_CMD_NEW,
> > >-	RDMA_NLDEV_CMD_DEL,
> > >
> > >-	RDMA_NLDEV_CMD_PORT_GET, /* can dump */
> > >-	RDMA_NLDEV_CMD_PORT_SET,
> > >-	RDMA_NLDEV_CMD_PORT_NEW,
> > >-	RDMA_NLDEV_CMD_PORT_DEL,
> > >+	/* 2 - 4 are free to use */
> > >
> > >-	RDMA_NLDEV_CMD_RES_GET, /* can dump */
> > >+	RDMA_NLDEV_CMD_PORT_GET = 5, /* can dump */
> > >+
> > >+	/* 6 - 8 are free to use */
> >
> > I don't see reason for the wholes.
>
> We are stuck with the holes, it is fixed uABI at this point, can't
> change the constants we actually implemented.
>
> > Also, Don't you use *_NEW for replies to *_GET, as it is common for
> > Netlink?
>
> It appears not..
>
> IMHO that convention makes the most sense when there is a GET/NEW pair
> with the idea the NEW is formed to be echoed back to the kernel -
> these case are all GET only..

Back then, I didn't find any reason to return _NEW, and I don't see it
now either.

There is NLM_F_ECHO flag for echo and sequence number to distinguish
between messages.

>
> Jason

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