tools: ynl: add header guards for nlctrl

I "extracted" YNL C into a GitHub repo to make it easier
to use in other projects: https://github.com/linux-netdev/ynl-c

GitHub actions use Ubuntu by default, and the kernel headers
there are missing f329a0ebeaba ("genetlink: correct uAPI defines").
Add the direct include workaround for nlctrl.

Fixes: 768e044a5fd4 ("doc/netlink/specs: Add spec for nlctrl netlink family")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://lore.kernel.org/r/20240315002108.523232-1-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

tools: ynl: protect from old OvS headers

Since commit 7c59c9c8f202 ("tools: ynl: generate code for ovs families")
we need relatively recent OvS headers to get YNL to compile.
Add the direct include workaround to fix compilation on less
up-to-date OSes like CentOS 9.

Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://lore.kernel.org/r/20240226225806.1301152-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools: ynl: fix header guards

devlink and ethtool have a trailing _ in the header guard. I must have
copy/pasted it into new guards, assuming it's a headers_install artifact.

This fixes build if system headers are old.

Fixes: 8f109e91b852 ("tools: ynl: include dpll and mptcp_pm in C codegen")
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20240222234831.179181-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools: ynl: include dpll and mptcp_pm in C codegen

The DPLL and mptcp_pm families are pretty clean, and YNL C codegen
supports them fully with no changes. Add them to user space codegen
so that C samples can be written, and we know immediately if changes
to these families require YNL codegen work.

Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20240202004926.447803-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools: ynl: fix header path for nfsd

The makefile dependency is trying to include the wrong header:

<command-line>: fatal error: ../../../../include/uapi//linux/nfsd.h: No such file or directory

The guard also looks wrong.

Fixes: f14122b2c2ac ("tools: ynl: Add source files for nfsd netlink protocol")
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20231123030624.1611925-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools: ynl: Add source files for nfsd netlink protocol

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

tools: ynl: improve the direct-include header guard logic

Przemek suggests that I shouldn't accuse GCC of witchcraft,
there is a simpler explanation for why we need manual define.

scripts/headers_install.sh modifies the guard, removing _UAPI.
That's why including a kernel header from the tree and from
/usr leads to duplicate definitions.

This also solves the mystery of why I needed to include
the header conditionally. I had the wrong guards for most
cases but ethtool.

Suggested-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Link: https://lore.kernel.org/r/20230621231719.2728928-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools: ynl: work around stale system headers

The inability to include the uAPI headers directly in tools/
is one of the bigger annoyances of compiling user space code.
Most projects trade the pain for smaller inconvenience of having
to copy the headers under tools/include.

In case of netlink headers I think that we can avoid both.
Netlink family headers are simple and should be self-contained.
We can try to twiddle the Makefile a little to force-include
just the family header, and use system headers for the rest.

This works fairly well. There are two warts - for some reason
if we specify -include $path/family.h as a compilation flag,
the #ifdef header guard does not seem to work. So we need
to throw the guard in on the command line as well. Seems like
GCC detects that the header is different and tries to include
both. Second problem is that make wants hash sign to be escaped
or not depending on the version. Sigh.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>