arch/um/drivers/random.c:31:31: sparse: sparse: Using plain integer as NULL pointer

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   0f4498cef9f5cd18d7c6639a2a902ec1edc5be4e
commit: 72d3e093afae79611fa38f8f2cfab9a888fe66f2 um: random: Register random as hwrng-core device
date:   3 months ago
config: um-randconfig-s031-20210327 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.3-277-gc089cd2d-dirty
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=72d3e093afae79611fa38f8f2cfab9a888fe66f2
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 72d3e093afae79611fa38f8f2cfab9a888fe66f2
        # save the attached .config to linux build tree
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=um 

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


sparse warnings: (new ones prefixed by >>)
>> arch/um/drivers/random.c:31:31: sparse: sparse: Using plain integer as NULL pointer

vim +31 arch/um/drivers/random.c

    25	
    26	/* Changed at init time, in the non-modular case, and at module load
    27	 * time, in the module case.  Presumably, the module subsystem
    28	 * protects against a module being loaded twice at the same time.
    29	 */
    30	static int random_fd = -1;
  > 31	static struct hwrng hwrng = { 0, };
    32	static DECLARE_COMPLETION(have_data);
    33	

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Attachment: .config.gz
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