Re: [PATCH] net: dsa: qca8k: reset cpu port on MTU change

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Jun 28, 2022 at 04:30:10PM +0200, Christian Marangi wrote:
> commit 386228c694bf1e7a7688e44412cb33500b0ac585 upstream.
> 
> It was discovered that the Documentation lacks of a fundamental detail
> on how to correctly change the MAX_FRAME_SIZE of the switch.
> 
> In fact if the MAX_FRAME_SIZE is changed while the cpu port is on, the
> switch panics and cease to send any packet. This cause the mgmt ethernet
> system to not receive any packet (the slow fallback still works) and
> makes the device not reachable. To recover from this a switch reset is
> required.
> 
> To correctly handle this, turn off the cpu ports before changing the
> MAX_FRAME_SIZE and turn on again after the value is applied.
> 
> Fixes: f58d2598cf70 ("net: dsa: qca8k: implement the port MTU callbacks")
> Cc: stable@vger.kernel.org
> Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
> Link: https://lore.kernel.org/r/20220621151122.10220-1-ansuelsmth@gmail.com
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> [ backport: fix conflict using the old port_sts struct instead of bitmap ]
> ---
>  drivers/net/dsa/qca8k.c | 23 +++++++++++++++++++++--
>  1 file changed, 21 insertions(+), 2 deletions(-)

This only applied to 5.15.y and 5.18.y, what about 5.10.y?  Please give
us a hint as to what kernel(s) a backport is for when sending them.

thanks,

greg k-h