Re: did vfs_read or something related to it get broken?

[David F.]

Answer: No nothing got broken except the driver itself.

On Fri, Jun 30, 2017 at 4:10 PM, David F. <df7729@xxxxxxxxx> wrote:
> Hi,
>
> I have a driver that reads data from a file that has worked from
> kernel 3.x up to 4.9.13.  I haven't tried all the other 4.9's or 4.10,
> or 4.11.6 or earlier, but in 4.11.7 it's now broken and an error is
> returned.   It's based on
> http://krishnamohanlinux.blogspot.com/2013/12/how-to-write-to-file-from-kernel-module.html
>
> Is there a new requirement of some sort or did it get broken?
>
> int driver_file_read(struct file *file, unsigned char *data, unsigned int size)
> {
>   int ret;
>   mm_segment_t oldfs;
>
>   // get file pointer
>   loff_t pos = file->f_pos;
>
>   oldfs   = get_fs();
>   set_fs(get_ds());
>
>   ret=vfs_read(file, data, size, &pos);
>
>   set_fs(oldfs);
>
>   // update file pointer
>   file->f_pos=pos;
>
>    return (ret);
> }
>
>
> struct file *driver_file_open(const char *path, int flags, int mode, int *err)
> {
>   int ec=0;
>   struct file *filp = NULL;
>   filp=filp_open(path, flags, mode);
>   if (IS_ERR(filp)) {
>     ec=PTR_ERR(filp);
>     filp=NULL;
>   }
>   // update callers error code
>   if (err) {
>     *err=ec;
>   }
>   // return pointer to file
>   return (filp);
> }