Re: [PATCH v2] iTCO_wdt: mask NMI_NOW bit for update_no_reboot_bit() call

[kernel test robot]

Hi Oleksandr,

kernel test robot noticed the following build warnings:

[auto build test WARNING on westeri-thunderbolt/next]
[also build test WARNING on linus/master v6.11-rc7 next-20240912]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Oleksandr-Ocheretnyi/iTCO_wdt-mask-NMI_NOW-bit-for-update_no_reboot_bit-call/20240912-222231
base:   https://git.kernel.org/pub/scm/linux/kernel/git/westeri/thunderbolt.git next
patch link:    https://lore.kernel.org/r/20240912141931.2447826-1-oocheret%40cisco.com
patch subject: [PATCH v2] iTCO_wdt: mask NMI_NOW bit for update_no_reboot_bit() call
config: i386-buildonly-randconfig-003-20240913 (https://download.01.org/0day-ci/archive/20240913/202409131302.oGABipcM-lkp@xxxxxxxxx/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240913/202409131302.oGABipcM-lkp@xxxxxxxxx/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202409131302.oGABipcM-lkp@xxxxxxxxx/

All warnings (new ones prefixed by >>):

   drivers/watchdog/iTCO_wdt.c: In function 'update_no_reboot_bit_cnt':
>> drivers/watchdog/iTCO_wdt.c:226:33: warning: conversion from 'long unsigned int' to 'u16' {aka 'short unsigned int'} changes value from '4294967039' to '65279' [-Woverflow]
     226 |         u16 val, newval, mask = (~NMI_NOW);
         |                                 ^


vim +226 drivers/watchdog/iTCO_wdt.c

   222	
   223	static int update_no_reboot_bit_cnt(void *priv, bool set)
   224	{
   225		struct iTCO_wdt_private *p = priv;
 > 226		u16 val, newval, mask = (~NMI_NOW);
   227	
   228		/* writing back 1b1 to NMI_NOW of TCO1_CNT register
   229		 * causes NMI_NOW bit inversion what consequently does
   230		 * not allow to perform the register's value comparison
   231		 * properly.
   232		 *
   233		 * NMI_NOW bit masking for TCO1_CNT register values
   234		 * helps to avoid possible NMI_NOW bit inversions on
   235		 * following write operation.
   236		 */
   237		val = inw(TCO1_CNT(p)) & mask;
   238		if (set)
   239			val |= BIT(0);
   240		else
   241			val &= ~BIT(0);
   242		outw(val, TCO1_CNT(p));
   243		newval = inw(TCO1_CNT(p)) & mask;
   244	
   245		/* make sure the update is successful */
   246		return val != newval ? -EIO : 0;
   247	}
   248	

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