Re: [PATCH net] net: dsa: refuse cross-chip mirroring operations

[Andrew Lunn]

On Tue, Oct 08, 2024 at 12:43:20PM +0300, Vladimir Oltean wrote:
> In case of a tc mirred action from one switch to another, the behavior
> is not correct. We simply tell the source switch driver to program a
> mirroring entry towards mirror->to_local_port = to_dp->index, but it is
> not even guaranteed that the to_dp belongs to the same switch as dp.
> 
> For proper cross-chip support, we would need to go through the
> cross-chip notifier layer in switch.c, program the entry on cascade
> ports, and introduce new, explicit API for cross-chip mirroring, given
> that intermediary switches should have introspection into the DSA tags
> passed through the cascade port (and not just program a port mirror on
> the entire cascade port). None of that exists today.
> 
> Reject what is not implemented so that user space is not misled into
> thinking it works.
> 
> Fixes: f50f212749e8 ("net: dsa: Add plumbing for port mirroring")
> Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>

Reviewed-by: Andrew Lunn <andrew@xxxxxxx>

    Andrew