Re: drivers/tty/serial/serial_core.c:621 uart_write_room() warn: unsigned 'ret' is never less than zero.

[Tony Lindgren <tony@atomide.com>]

* kernel test robot <lkp@intel.com> [210928 11:48]:
> tree:   https://github.com/0day-ci/linux/commits/Tony-Lindgren/Get-rid-of-pm_runtime_irq_safe-for-8250_omap/20210922-152808
> head:   4456f28c1932b70461a0d8c45d4e863fa9d1be29
> commit: 3c7e2a8d4353263d8c5607fc7eca5e4b009f45eb serial: core: Add new prep_tx for power management
> date:   6 days ago
> config: i386-randconfig-m021-20210927 (attached as .config)
> compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> 
> New smatch warnings:
> drivers/tty/serial/serial_core.c:621 uart_write_room() warn: unsigned 'ret' is never less than zero.
> 
> Old smatch warnings:
> drivers/tty/serial/serial_core.c:308 uart_shutdown() error: we previously assumed 'uport' could be null (see line 304)
> drivers/tty/serial/serial_core.c:329 uart_shutdown() error: uninitialized symbol 'flags'.
> drivers/tty/serial/serial_core.c:2753 iomem_base_show() warn: argument 3 to %lX specifier is cast from pointer

FYI, this patch is no longer needed, updated series posted at [0] below.

Thanks,

Tony

[0] https://lore.kernel.org/linux-kernel/20210930062906.58937-1-tony@atomide.com/T/#m8aa4dc5d38218d17c652d45d3611fc8a696b96c1