netdev - Re: [PATCH net-next v2 0/2] bridge: make setlink/dellink notifications more accurate

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Message-ID: <43f36fb0-8543-7e60-a80e-6da35d74b69a@cumulusnetworks.com>
Date:   Thu, 26 Oct 2017 00:49:11 +0300
From:   Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:     netdev@...r.kernel.org
Cc:     roopa@...ulusnetworks.com, dsa@...ulusnetworks.com,
        mrv@...atatu.com, stephen@...workplumber.org,
        bridge@...ts.linux-foundation.org
Subject: Re: [PATCH net-next v2 0/2] bridge: make setlink/dellink
 notifications more accurate

On 24/10/17 15:32, Nikolay Aleksandrov wrote:
> Hi,
> Before this set the bridge would generate a notification on vlan add or del
> even if they didn't actually do any changes, which confuses listeners and
> is generally not preferred. We could also lose notifications on actual
> changes if one adds a range of vlans and there's an error in the middle.
> The problem with just breaking and returning an error is that we could
> break existing user-space scripts which rely on the vlan delete to clear
> all existing entries in the specified range and ignore the non-existing
> errors (typically used to clear the current vlan config).
> So in order to make the notifications more accurate while keeping backwards
> compatibility we add a boolean that tracks if anything actually changed
> during the config calls.
> 
> The vlan add is more difficult to fix because it always returns 0 even if
> nothing changed, but we cannot use a specific error because the drivers
> can return anything and we may mask it, also we'd need to update all places
> that directly return the add result, thus to signal that a vlan was created
> or updated and in order not to break overlapping vlan range add we pass
> down the new boolean that tracks changes to the add functions to check
> if anything was actually updated.
> 
> Can't say that I am happy with this change, but currently I don't see any
> simpler way which doesn't affect user-space.
> 
> v2: pass changed down to vlan add instead of masking errors
> 
> Thanks,
>  Nik
> 
> Nikolay Aleksandrov (2):
>   bridge: netlink: make setlink/dellink notifications more accurate
>   bridge: vlan: signal if anything changed on vlan add
> 
>  net/bridge/br_netlink.c        | 51 ++++++++++++++++-----------
>  net/bridge/br_netlink_tunnel.c | 14 +++++---
>  net/bridge/br_private.h        |  6 ++--
>  net/bridge/br_private_tunnel.h |  3 +-
>  net/bridge/br_vlan.c           | 78 ++++++++++++++++++++++++++++++------------
>  5 files changed, 102 insertions(+), 50 deletions(-)
> 

Ah, forgot to update the non-vlan bridge config case with the empty stubs,
will send a fixed and tested v3 asap.