linux-kernel - [jsarha:topic/cros-sof-v4.19 949/6555] mm/low-mem-notify.c:87:16: sparse: sparse: incorrect type in return expression (different base types)

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Date:   Thu, 12 May 2022 10:00:34 +0800
From:   kernel test robot <lkp@...el.com>
To:     Guenter Roeck <groeck@...omium.org>
Cc:     kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org,
        Luigi Semenzato <semenzato@...omium.org>
Subject: [jsarha:topic/cros-sof-v4.19 949/6555] mm/low-mem-notify.c:87:16:
 sparse: sparse: incorrect type in return expression (different base types)

tree:   https://github.com/jsarha/linux topic/cros-sof-v4.19
head:   d7a3e91d8d16d1ef8653deec5a1fffc4de034a0c
commit: b7ec7fb624dfc8d07e722cf2e0e72ff82ebaec7b [949/6555] CHROMIUM: low-mem: Fix return type of low_mem_notify_poll
config: i386-randconfig-s001-20220509 (https://download.01.org/0day-ci/archive/20220512/202205120909.GVWyvFOU-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.2.0-20) 11.2.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-dirty
        # https://github.com/jsarha/linux/commit/b7ec7fb624dfc8d07e722cf2e0e72ff82ebaec7b
        git remote add jsarha https://github.com/jsarha/linux
        git fetch --no-tags jsarha topic/cros-sof-v4.19
        git checkout b7ec7fb624dfc8d07e722cf2e0e72ff82ebaec7b
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=i386 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>


sparse warnings: (new ones prefixed by >>)
>> mm/low-mem-notify.c:87:16: sparse: sparse: incorrect type in return expression (different base types) @@     expected restricted __poll_t @@     got unsigned int [assigned] ret @@
   mm/low-mem-notify.c:87:16: sparse:     expected restricted __poll_t
   mm/low-mem-notify.c:87:16: sparse:     got unsigned int [assigned] ret

vim +87 mm/low-mem-notify.c

89587e9d1c30b5 Luigi Semenzato 2014-04-03  74  
b7ec7fb624dfc8 Guenter Roeck   2018-11-01  75  static __poll_t low_mem_notify_poll(struct file *file, poll_table *wait)
89587e9d1c30b5 Luigi Semenzato 2014-04-03  76  {
89587e9d1c30b5 Luigi Semenzato 2014-04-03  77  	unsigned int ret = 0;
89587e9d1c30b5 Luigi Semenzato 2014-04-03  78  
89587e9d1c30b5 Luigi Semenzato 2014-04-03  79  	/* Update state to reflect any recent freeing. */
89587e9d1c30b5 Luigi Semenzato 2014-04-03  80  	atomic_set(&low_mem_state, is_low_mem_situation());
89587e9d1c30b5 Luigi Semenzato 2014-04-03  81  
89587e9d1c30b5 Luigi Semenzato 2014-04-03  82  	poll_wait(file, &low_mem_wait, wait);
89587e9d1c30b5 Luigi Semenzato 2014-04-03  83  
1fa6b9516423e6 Luigi Semenzato 2012-04-18  84  	if (low_mem_margin_enabled && atomic_read(&low_mem_state) != 0)
89587e9d1c30b5 Luigi Semenzato 2014-04-03  85  		ret = POLLIN;
89587e9d1c30b5 Luigi Semenzato 2014-04-03  86  
89587e9d1c30b5 Luigi Semenzato 2014-04-03 @87  	return ret;
89587e9d1c30b5 Luigi Semenzato 2014-04-03  88  }
89587e9d1c30b5 Luigi Semenzato 2014-04-03  89  

:::::: The code at line 87 was first introduced by commit
:::::: 89587e9d1c30b5f908d4bfe5f2ee0b920c156c14 CHROMIUM: Add /dev/low-mem device for low-memory notification.

:::::: TO: Luigi Semenzato <semenzato@...omium.org>
:::::: CC: Guenter Roeck <groeck@...omium.org>

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