Re: [PATCH] virtio_console: Assure used length from device is limited

[kernel test robot <lkp@intel.com>]

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Hi Xie,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on char-misc/char-misc-testing]
[also build test WARNING on v5.13-rc3 next-20210525]
[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]

url:    https://github.com/0day-ci/linux/commits/Xie-Yongji/virtio_console-Assure-used-length-from-device-is-limited/20210525-125848
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git 281e468446994a7672733af2bf941f4110d4a895
config: x86_64-randconfig-a001-20210525 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 99155e913e9bad5f7f8a247f8bb3a3ff3da74af1)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://github.com/0day-ci/linux/commit/edaca17a036c98c3e0f6953318976caff7168a6e
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Xie-Yongji/virtio_console-Assure-used-length-from-device-is-limited/20210525-125848
        git checkout edaca17a036c98c3e0f6953318976caff7168a6e
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

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

All warnings (new ones prefixed by >>):

>> drivers/char/virtio_console.c:478:14: warning: comparison of distinct pointer types ('typeof (len) *' (aka 'unsigned int *') and 'typeof (buf->size) *' (aka 'unsigned long *')) [-Wcompare-distinct-pointer-types]
                   buf->len = min(len, buf->size);
                              ^~~~~~~~~~~~~~~~~~~
   include/linux/minmax.h:51:19: note: expanded from macro 'min'
   #define min(x, y)       __careful_cmp(x, y, <)
                           ^~~~~~~~~~~~~~~~~~~~~~
   include/linux/minmax.h:42:24: note: expanded from macro '__careful_cmp'
           __builtin_choose_expr(__safe_cmp(x, y), \
                                 ^~~~~~~~~~~~~~~~
   include/linux/minmax.h:32:4: note: expanded from macro '__safe_cmp'
                   (__typecheck(x, y) && __no_side_effects(x, y))
                    ^~~~~~~~~~~~~~~~~
   include/linux/minmax.h:18:28: note: expanded from macro '__typecheck'
           (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
                      ~~~~~~~~~~~~~~ ^  ~~~~~~~~~~~~~~
   drivers/char/virtio_console.c:1712:14: warning: comparison of distinct pointer types ('typeof (len) *' (aka 'unsigned int *') and 'typeof (buf->size) *' (aka 'unsigned long *')) [-Wcompare-distinct-pointer-types]
                   buf->len = min(len, buf->size);
                              ^~~~~~~~~~~~~~~~~~~
   include/linux/minmax.h:51:19: note: expanded from macro 'min'
   #define min(x, y)       __careful_cmp(x, y, <)
                           ^~~~~~~~~~~~~~~~~~~~~~
   include/linux/minmax.h:42:24: note: expanded from macro '__careful_cmp'
           __builtin_choose_expr(__safe_cmp(x, y), \
                                 ^~~~~~~~~~~~~~~~
   include/linux/minmax.h:32:4: note: expanded from macro '__safe_cmp'
                   (__typecheck(x, y) && __no_side_effects(x, y))
                    ^~~~~~~~~~~~~~~~~
   include/linux/minmax.h:18:28: note: expanded from macro '__typecheck'
           (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
                      ~~~~~~~~~~~~~~ ^  ~~~~~~~~~~~~~~
   2 warnings generated.


vim +478 drivers/char/virtio_console.c

   466	
   467	/* Callers should take appropriate locks */
   468	static struct port_buffer *get_inbuf(struct port *port)
   469	{
   470		struct port_buffer *buf;
   471		unsigned int len;
   472	
   473		if (port->inbuf)
   474			return port->inbuf;
   475	
   476		buf = virtqueue_get_buf(port->in_vq, &len);
   477		if (buf) {
 > 478			buf->len = min(len, buf->size);
   479			buf->offset = 0;
   480			port->stats.bytes_received += len;
   481		}
   482		return buf;
   483	}
   484	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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