RE: [net-next 0/4] devlink: add dry run support for flash update

-----Original Message-----
From: Jakub Kicinski <kuba@kernel.org>
Sent: Friday, October 08, 2021 3:36 PM
To: Keller, Jacob E <jacob.e.keller@intel.com>
Cc: Jiri Pirko <jiri@resnulli.us>; netdev@vger.kernel.org
Subject: Re: [net-next 0/4] devlink: add dry run support for flash update

On Fri, 8 Oct 2021 21:43:32 +0000 Keller, Jacob E wrote:

quoted

quoted

quoted

Hmm, old kernel vs. new-userspace, the requested dry-run, won't be
really dry run. I guess that user might be surprised in that case...

Would it be enough to do a policy dump in user space to check attr is
recognized and add a warning that this is required next to the attr
in the uAPI header?

Doesn't the policy checks prevent any unknown attributes?
Or are unknown attributes silently ignored?

Did you test it?

DEVLINK_CMD_FLASH_UPDATE has GENL_DONT_VALIDATE_STRICT set.

Hmm. I did run into an issue while initially testing where DEVLINK_ATTR_DRY_RUN wasn't in the devlink_nla_policy table and it rejected the command with an unknown attribute. I had to add the attribute to the policy table to fix this.

I'm double checking on a different kernel now with the new userspace to see if I get the same behavior.

I'm not super familiar with the validation code or what GENL_DONT_VALIDATE_STRICT means...

Indeed.. I just did a search for GENL_DONT_VALIDATE_STRICT and the only uses I can find are ones which *set* the flag. Nothing ever checks it!!

I suspect it got removed at some point.. still digging into exact history though...