[Skiboot] [PATCH v2 2/2] uart: Drop console write data if BMC becomes unresponsive

[Oliver O'Halloran]

On Fri, May 22, 2020 at 1:50 AM Vasant Hegde
<hegdevasant at linux.vnet.ibm.com> wrote:
>
> If BMC becomes unresponsive (ex: during BMC reboot) during console write
> then we may get stuck in uart_wait_tx_room(). This will result in CPU
> to get stuck in OPAL. This will result in kernel lockups and in some
> cases host becomes unresponsive.
>
> This patch introduces timeout option. If UART operation doesn't complete
> within predefined time then it will drop write data and comes out.
>
> Note that this patch fixes both OPAL internal console as well as
> console write APIs.
>
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> [Various fixes on top of Nick's proposal to have single timer - Vasant]
> Signed-off-by: Vasant Hegde <hegdevasant at linux.vnet.ibm.com>

Thanks, patch merged as 6bf21350da32776aac8ba75bf48933854647bd7e.

I've dropped Patch 1/2 since I don't think it's fixing a real problem,
just a red-herring we found along the way.

Oliver