Bad address problem while reading from hard disk(using sys_read).

Bad address problem while reading from hard disk(using sys_read).

[BalaKrishna Mallipeddi]

Hi,
    I developed a kernel module. Within that i am
dynamically allocating memory(using kmalloc and
vmalloc) for a buffer to read data. After that while
trying to read into this buffer from the hard disk
using sys_read i am getting an error. And the same
error i am getting while writing into another buffer,
which was allocated in the same way, using sys_write.
The error number set is -14(EFAULT) i.e., Bad address.


   Give me any idea to resolve the problem.

  If anyone help me i am gretful to them.

Thanks & Regards


=====
BalaKrishna Mallipeddi
Member Technical Staff Software
Innomedia Technologies Pvt. Ltd.,
#3278, 12th Main, HAL 2nd stage,
Bangalore-560008,
INDIA
Phone : 5278389 + 123

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Re: Bad address problem while reading from hard disk(using sys_read).

[Davide Libenzi]

On Fri, 20 Jun 2003, BalaKrishna Mallipeddi wrote:

> Hi,
>     I developed a kernel module. Within that i am
> dynamically allocating memory(using kmalloc and
> vmalloc) for a buffer to read data. After that while
> trying to read into this buffer from the hard disk
> using sys_read i am getting an error. And the same
> error i am getting while writing into another buffer,
> which was allocated in the same way, using sys_write.
> The error number set is -14(EFAULT) i.e., Bad address.
>
>
>    Give me any idea to resolve the problem.
>
>   If anyone help me i am gretful to them.

All sys_* functions expect user space addresses and you passing a kernel
space one. You need something like :

        mm_segment_t oldfs;

	oldfs = get_fs();
        set_fs(KERNEL_DS);
        nread = sys_read(fd, buf, cnt);
        set_fs(oldfs);

(If you really want to do that)



- Davide