Re: [PATCH iproute2-next v3 8/8] iplink: Reduce number of arguments to iplink_parse()

Serhey Popovych wrote:

David Ahern wrote:

quoted

On 2/26/18 11:20 AM, Serhey Popovych wrote:

quoted

Stephen Hemminger wrote:

quoted

On Thu, 22 Feb 2018 15:02:06 +0200
Serhey Popovych [off-list ref] wrote:

quoted

+struct iplink_parse_args {
+	const char *dev;
+	const char *name;
+	const char *type;
+
+	/* This definitely must be the last one and initialized
+	 * by the caller of iplink_parse() that will initialize rest.
+	 */
+	struct iplink_req *req;
+};
+

No control block please.

Accepted.

quoted

If you have too many arguments, then that means you need to do
some refactoring.

So using structure as single argument to a function isn't an option?

quoted

As I mentioned before, iplink_parse should not be used by vxcan or veth
as they only want a subset of the parsing. Once you take those users
out, iplink_parse becomes local to iplink.c with a single user. In which
case I suspect the compiler will always inline the function so no
refactoring on the number of arguments is needed.

I will implement cut down function to parse vxcan and veth peer device
parameters and reuse it in iplink_parse() to avoid code duplications.

But my final goal not to refactor on number of arguments to parse,
that's side product of this series, I want to take @name, @dev and
other parameters for later use. In ->parse_opt() modules @name, @dev
and others are not available easily. It seems only way to get them is
to parse supplied netlink buffer.

While looking on how to make iplink_parse_light() that will be used with
vxcan and veth I found following problems:

  1) need to copy nearly all parameters parsing code (except vf, alias,
     carrier, master, protodown, link-netnsid, addrgenmode). this will
     be mitigated by re using iplink_parse_light() in iplink_parse()

  2) how to add attributes like IFLA_GROUP? in caller? this will give
     even more code duplications.

  3) there is high risk of adding regression either via conflicting
     matches() parameter in userspace or missing kernel attribute
     previously supported.

Sorry, I do not like this approach. I do not want to broke anything,
I just want @name and @dev parameters in ->parse_opt().


  2)