Re: [PATCH] mm: Use BUG_ON directly instead of a if condition followed by BUG

[kbuild test robot]

Hi zhong,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v4.19-rc3 next-20180910]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/zhong-jiang/mm-Use-BUG_ON-directly-instead-of-a-if-condition-followed-by-BUG/20180911-025008
config: x86_64-randconfig-x012-201836 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   mm/memory_hotplug.c: In function 'remove_memory':
>> mm/memory_hotplug.c:1891:9: error: macro "BUG" passed 1 arguments, but takes just 0
     BUG(ret);
            ^
>> mm/memory_hotplug.c:1891:2: error: 'BUG' undeclared (first use in this function)
     BUG(ret);
     ^~~
   mm/memory_hotplug.c:1891:2: note: each undeclared identifier is reported only once for each function it appears in

vim +/BUG +1891 mm/memory_hotplug.c

  1865	
  1866	/**
  1867	 * remove_memory
  1868	 * @nid: the node ID
  1869	 * @start: physical address of the region to remove
  1870	 * @size: size of the region to remove
  1871	 *
  1872	 * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
  1873	 * and online/offline operations before this call, as required by
  1874	 * try_offline_node().
  1875	 */
  1876	void __ref remove_memory(int nid, u64 start, u64 size)
  1877	{
  1878		int ret;
  1879	
  1880		BUG_ON(check_hotplug_memory_range(start, size));
  1881	
  1882		mem_hotplug_begin();
  1883	
  1884		/*
  1885		 * All memory blocks must be offlined before removing memory.  Check
  1886		 * whether all memory blocks in question are offline and trigger a BUG()
  1887		 * if this is not the case.
  1888		 */
  1889		ret = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL,
  1890					check_memblock_offlined_cb);
> 1891		BUG(ret);

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