Re: [PATCH net-next] net: core: devlink: add new trap action HARD_DROP

On Thu, 21 Jan 2021 14:21:52 +0200 Ido Schimmel wrote:

On Thu, Jan 21, 2021 at 01:29:37PM +0200, Oleksandr Mazur wrote:

quoted

Add new trap action HARD_DROP, which can be used by the
drivers to register traps, where it's impossible to get
packet reported to the devlink subsystem by the device
driver, because it's impossible to retrieve dropped packet
from the device itself.
In order to use this action, driver must also register
additional devlink operation - callback that is used
to retrieve number of packets that have been dropped by
the device.  

Are these global statistics about number of packets the hardware dropped
for a specific reason or are these per-port statistics?

It's a creative use of devlink-trap interface, but I think it makes
sense. Better to re-use an existing interface than creating yet another
one.

Not sure if I agree, if we can't trap why is it a trap?
It's just a counter.

It's just another ACTION for trap item. Action however can be switched, e.g. from HARD_DROP to MIRROR.

The thing is to be able to configure specific trap to be dropped, and provide a way for the device to report back how many packets have been dropped.
If device is able to report the packet itself, then devlink would be in charge of counting. If not, there should be a way to retrieve these statistics from the devlink.