On Fri, Mar 02, 2018 at 09:21:56AM -0500, Alexander Aring wrote:

Hi,

On Fri, Mar 2, 2018 at 3:37 AM, Jiri Pirko [off-list ref] wrote:

quoted

Fri, Mar 02, 2018 at 04:48:40AM CET, kubakici@wp.pl wrote:

quoted

On Thu, 1 Mar 2018 22:38:50 -0500, Alexander Aring wrote:

quoted

I guess to make extack working, you need to return an errno if failed.

AFAIK extack is printed as a warning if operation did not fail.

Yes, I checked this and it is printed as warning.

ouch, so far I know extack it allows only one messages delivered back
to the user space.

If we introduce a warning in the successful path here, it could be
that in the callpath (after "successful" part of this callback), that
somebody else want to add a warning and overwrites actually your
warning (even, he is not aware that this warning was set - okay I
suppose you can do another check on NULL and set a warning, that
somebody overwrites a warning :-D).

If extack messages get's append and is some kind of for_each_nested
string in netlink -> we have no problem, but I guess this not how it's
working. :-/

IOW I guess what we are looking for here is a way to use extack to
track more than an error/warning message, but to be a bit more
complete error reporting tool.

The case here is pretty much like the case with tc flower offloading,
to issue a message when it couldn't offload while it wasn't fatal for
the rule (in case SKIP_SW wasn't specified). The reason for why the
offloading couldn't happen could have been a temporary one and such
log of a warning is important for troubleshooting.

  Marcelo