Hi Dmitry,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on tty/tty-testing]
[also build test WARNING on next-20200110]
[cannot apply to linux/master usb/usb-testing linus/master v5.5-rc5]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Dmitry-Safonov/serial-sysrq-Add-MAGIC_SYSRQ_SERIAL_SEQUENCE/20200110-191606
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git tty-testing

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

New smatch warnings:
drivers/tty/serial/serial_core.c:3105 uart_try_toggle_sysrq() warn: unsigned '++port->sysrq_seq' is never less than zero.

Old smatch warnings:
drivers/tty/serial/serial_core.c:295 uart_shutdown() error: we previously assumed 'uport' could be null (see line 291)
drivers/tty/serial/serial_core.c:2729 uart_get_attr_iomem_base() warn: argument 4 to %lX specifier is cast from pointer

vim +3105 drivers/tty/serial/serial_core.c

  3092	
  3093	static int uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch)
  3094	{
  3095		if (sysrq_toggle_seq[0] == '\0')
  3096			return 0;
  3097	
  3098		BUILD_BUG_ON(ARRAY_SIZE(sysrq_toggle_seq) >= sizeof(port->sysrq_seq)*U8_MAX);
  3099		if (sysrq_toggle_seq[port->sysrq_seq] != ch) {
  3100			port->sysrq_seq = 0;
  3101			return 0;
  3102		}
  3103	
  3104		/* Without the last \0 */
> 3105		if (++port->sysrq_seq < (ARRAY_SIZE(sysrq_toggle_seq) - 1)) {
  3106			port->sysrq = jiffies + HZ*5;
  3107			return 1;
  3108		}
  3109	
  3110		schedule_work(&sysrq_enable_work);
  3111	
  3112		port->sysrq = 0;
  3113		return 1;
  3114	}
  3115	

---
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