Re: [PATCH 2/2] virtio-rng: add sysfs entries for leak detection

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

Hi Babis,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on char-misc/char-misc-testing]
[also build test WARNING on char-misc/char-misc-next char-misc/char-misc-linus linus/master v6.2-rc4 next-20230119]
[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/Babis-Chalios/virtio-rng-implement-entropy-leak-feature/20230120-024631
patch link:    https://lore.kernel.org/r/20230119184349.74072-3-bchalios%40amazon.es
patch subject: [PATCH 2/2] virtio-rng: add sysfs entries for leak detection
config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20230120/202301200640.CsblwTsa-lkp@intel.com/config)
compiler: m68k-linux-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/2a801d93b8225555e4cb293a173e2053870cb2d1
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Babis-Chalios/virtio-rng-implement-entropy-leak-feature/20230120-024631
        git checkout 2a801d93b8225555e4cb293a173e2053870cb2d1
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=m68k olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash drivers/char/

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

All warnings (new ones prefixed by >>):

>> drivers/char/hw_random/virtio-rng.c:61:9: warning: no previous prototype for 'virtrng_sysfs_read' [-Wmissing-prototypes]
      61 | ssize_t virtrng_sysfs_read(struct file *filep, struct kobject *kobj,
         |         ^~~~~~~~~~~~~~~~~~
>> drivers/char/hw_random/virtio-rng.c:76:5: warning: no previous prototype for 'virtrng_sysfs_mmap' [-Wmissing-prototypes]
      76 | int virtrng_sysfs_mmap(struct file *filep, struct kobject *kobj,
         |     ^~~~~~~~~~~~~~~~~~
   drivers/char/hw_random/virtio-rng.c:106:5: warning: no previous prototype for 'add_fill_on_leak_request' [-Wmissing-prototypes]
     106 | int add_fill_on_leak_request(struct virtrng_info *vi, struct virtqueue *vq, void *data, size_t len)
         |     ^~~~~~~~~~~~~~~~~~~~~~~~
   drivers/char/hw_random/virtio-rng.c:120:5: warning: no previous prototype for 'virtrng_fill_on_leak' [-Wmissing-prototypes]
     120 | int virtrng_fill_on_leak(struct virtrng_info *vi, void *data, size_t len)
         |     ^~~~~~~~~~~~~~~~~~~~
   drivers/char/hw_random/virtio-rng.c:141:5: warning: no previous prototype for 'add_copy_on_leak_request' [-Wmissing-prototypes]
     141 | int add_copy_on_leak_request(struct virtrng_info *vi, struct virtqueue *vq,
         |     ^~~~~~~~~~~~~~~~~~~~~~~~
   drivers/char/hw_random/virtio-rng.c:160:5: warning: no previous prototype for 'virtrng_copy_on_leak' [-Wmissing-prototypes]
     160 | int virtrng_copy_on_leak(struct virtrng_info *vi, void *to, void *from, size_t len)
         |     ^~~~~~~~~~~~~~~~~~~~


vim +/virtrng_sysfs_read +61 drivers/char/hw_random/virtio-rng.c

    59	
    60	#ifdef CONFIG_SYSFS
  > 61	ssize_t virtrng_sysfs_read(struct file *filep, struct kobject *kobj,
    62			struct bin_attribute *attr, char *buf, loff_t pos, size_t len)
    63	{
    64		struct virtrng_info *vi = attr->private;
    65		unsigned long gen_counter = *(unsigned long *)vi->map_buffer;
    66	
    67		if (!len)
    68			return 0;
    69	
    70		len = min(len, sizeof(gen_counter));
    71		memcpy(buf, &gen_counter, len);
    72	
    73		return len;
    74	}
    75	
  > 76	int virtrng_sysfs_mmap(struct file *filep, struct kobject *kobj,
    77			struct bin_attribute *attr, struct vm_area_struct *vma)
    78	{
    79		struct virtrng_info *vi = attr->private;
    80	
    81		if (vma->vm_pgoff || vma_pages(vma) > 1)
    82			return -EINVAL;
    83	
    84		if (vma->vm_flags & VM_WRITE)
    85			return -EPERM;
    86	
    87		vma->vm_flags |= VM_DONTEXPAND;
    88		vma->vm_flags &= ~VM_MAYWRITE;
    89	
    90		return vm_insert_page(vma, vma->vm_start, virt_to_page(vi->map_buffer));
    91	}
    92	#endif
    93	

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