Hi Arnaud,

I love your patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[cannot apply to v5.3-rc6 next-20190829]
[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/Arnaud-Pouliquen/rpmsg-core-add-API-to-get-message-length/20190829-222443
config: sparc64-allmodconfig (attached as .config)
compiler: sparc64-linux-gcc (GCC) 7.4.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.4.0 make.cross ARCH=sparc64 

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

All warnings (new ones prefixed by >>):

   In file included from include/linux/list.h:9:0,
                    from include/linux/module.h:9,
                    from drivers/tty/rpmsg_tty.c:7:
   drivers/tty/rpmsg_tty.c: In function 'rpmsg_tty_write':
   include/linux/kernel.h:821:29: warning: comparison of distinct pointer types lacks a cast
      (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
                                ^
   include/linux/kernel.h:835:4: note: in expansion of macro '__typecheck'
      (__typecheck(x, y) && __no_side_effects(x, y))
       ^~~~~~~~~~~
   include/linux/kernel.h:845:24: note: in expansion of macro '__safe_cmp'
     __builtin_choose_expr(__safe_cmp(x, y), \
                           ^~~~~~~~~~
   include/linux/kernel.h:854:19: note: in expansion of macro '__careful_cmp'
    #define min(x, y) __careful_cmp(x, y, <)
                      ^~~~~~~~~~~~~
>> drivers/tty/rpmsg_tty.c:152:13: note: in expansion of macro 'min'
     msg_size = min(len, msg_max_size);
                ^~~

vim +/min +152 drivers/tty/rpmsg_tty.c

   132	
   133	static int rpmsg_tty_write(struct tty_struct *tty, const u8 *buf, int len)
   134	{
   135		struct rpmsg_tty_port *cport = tty->driver_data;
   136		struct rpmsg_device *rpdev;
   137		ssize_t msg_max_size, msg_size;
   138		int ret;
   139		u8 *tmpbuf;
   140	
   141		/* If cts not set, the message is not sent*/
   142		if (!cport->cts)
   143			return 0;
   144	
   145		rpdev = cport->rpdev;
   146	
   147		dev_dbg(&rpdev->dev, "%s: send msg from tty->index = %d, len = %d\n",
   148			__func__, tty->index, len);
   149	
   150		msg_max_size = rpmsg_get_mtu(rpdev->ept);
   151	
 > 152		msg_size = min(len, msg_max_size);
   153		tmpbuf = kzalloc(msg_size, GFP_KERNEL);
   154		if (!tmpbuf)
   155			return -ENOMEM;
   156	
   157		memcpy(tmpbuf, buf, msg_size);
   158	
   159		/*
   160		 * Try to send the message to remote processor, if failed return 0 as
   161		 * no data sent
   162		 */
   163		ret = rpmsg_trysendto(cport->d_ept, tmpbuf, msg_size, cport->data_dst);
   164		kfree(tmpbuf);
   165		if (ret) {
   166			dev_dbg(&rpdev->dev, "rpmsg_send failed: %d\n", ret);
   167			return 0;
   168		}
   169	
   170		return msg_size;
   171	}
   172	

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