On 13/07/18 09:47, Li RongQing wrote:
> Once mtu_set_by_user is set to true, br_mtu_auto_adjust will
> not run, and no chance to clear mtu_set_by_user.
>
^^
This was by design, there is no error here and no "cleanup" is needed.
If you read the ndo_change_mtu() call you'll see the comment:
/* this flag will be cleared if the MTU was automatically adjusted */
It is the only way we can know that the MTU was automatically adjusted or set
by the user manually in which case we need to _stop_ automatically adjusting
MTU. This was done to be backwards compatible as much as possible but still
give the option to have user-configured MTU which doesn't disappear (and is
not overwritten).
So please next time read the original commit.
>From the original commit 804b854d374e ("net: bridge: disable bridge MTU auto
>tuning if it was set manually"):
" ...
Let's improve on that situation and allow for the user to
set any MTU within ETH_MIN/MAX limits, but once manually configured it
is the user's responsibility to keep it correct afterwards.
In case the MTU isn't manually set - the behaviour reverts to the
previous and the bridge follows the minimum MTU.
...
"
> and br_mtu_auto_adjust will run only if mtu_set_by_user is
> false, so not need to set it to false again
>
> Cc: Nikolay Aleksandrov <niko...@cumulusnetworks.com>
> Signed-off-by: Li RongQing <lirongq...@baidu.com>
> ---
> net/bridge/br_device.c | 1 -
> net/bridge/br_if.c | 4 ----
> 2 files changed, 5 deletions(-)
>
> diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
> index e682a668ce57..c636bc2749c2 100644
> --- a/net/bridge/br_device.c
> +++ b/net/bridge/br_device.c
> @@ -227,7 +227,6 @@ static int br_change_mtu(struct net_device *dev, int
> new_mtu)
>
> dev->mtu = new_mtu;
>
> - /* this flag will be cleared if the MTU was automatically adjusted */
> br->mtu_set_by_user = true;
> #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
> /* remember the MTU in the rtable for PMTU */
> diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
> index 05e42d86882d..47c65da4b1be 100644
> --- a/net/bridge/br_if.c
> +++ b/net/bridge/br_if.c
> @@ -450,11 +450,7 @@ void br_mtu_auto_adjust(struct net_bridge *br)
> if (br->mtu_set_by_user)
> return;
>
> - /* change to the minimum MTU and clear the flag which was set by
> - * the bridge ndo_change_mtu callback
> - */
> dev_set_mtu(br->dev, br_mtu_min(br));
> - br->mtu_set_by_user = false;
> }
>
> static void br_set_gso_limits(struct net_bridge *br)
>
Nacked-by: Nikolay Aleksandrov <niko...@cumulusnetworks.com>
