Re: [PATCH 1/3] dma-buf: Add ioctl to query mmap info

[kernel test robot <lkp@xxxxxxxxx>]

Hi Rob,

I love your patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v5.19-rc8]
[cannot apply to drm-misc/drm-misc-next drm/drm-next drm-exynos/exynos-drm-next drm-intel/for-linux-next drm-tip/drm-tip next-20220728]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Rob-Clark/dma-buf-map-info-support/20220730-010844
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 6e2c0490769ef8a95b61304389116ccc85c53e12
config: arc-randconfig-r043-20220729 (https://download.01.org/0day-ci/archive/20220730/202207300546.hB4U217w-lkp@xxxxxxxxx/config)
compiler: arceb-elf-gcc (GCC) 12.1.0
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
        # https://github.com/intel-lab-lkp/linux/commit/203f14a73a179d6c5fbfa4813e45fde2a9ae9860
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Rob-Clark/dma-buf-map-info-support/20220730-010844
        git checkout 203f14a73a179d6c5fbfa4813e45fde2a9ae9860
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arc SHELL=/bin/bash drivers/dma-buf/

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

All warnings (new ones prefixed by >>):

   drivers/dma-buf/dma-buf.c: In function 'dma_buf_info':
>> drivers/dma-buf/dma-buf.c:346:26: warning: passing argument 1 of 'copy_to_user' discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
     346 |         if (copy_to_user(uarg, &arg, sizeof(arg)))
         |                          ^~~~
   In file included from include/linux/sched/task.h:11,
                    from include/linux/sched/signal.h:9,
                    from include/linux/rcuwait.h:6,
                    from include/linux/percpu-rwsem.h:7,
                    from include/linux/fs.h:33,
                    from drivers/dma-buf/dma-buf.c:14:
   include/linux/uaccess.h:157:27: note: expected 'void *' but argument is of type 'const void *'
     157 | copy_to_user(void __user *to, const void *from, unsigned long n)
         |              ~~~~~~~~~~~~~^~


vim +346 drivers/dma-buf/dma-buf.c

   328	
   329	static long dma_buf_info(struct dma_buf *dmabuf, const void __user *uarg)
   330	{
   331		struct dma_buf_info arg;
   332	
   333		if (copy_from_user(&arg, uarg, sizeof(arg)))
   334			return -EFAULT;
   335	
   336		switch (arg.param) {
   337		case DMA_BUF_INFO_VM_PROT:
   338			if (!dmabuf->ops->mmap_info)
   339				return -ENOSYS;
   340			arg.value = dmabuf->ops->mmap_info(dmabuf);
   341			break;
   342		default:
   343			return -EINVAL;
   344		}
   345	
 > 346		if (copy_to_user(uarg, &arg, sizeof(arg)))
   347			return -EFAULT;
   348	
   349		return 0;
   350	}
   351	

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