On 11/12/05, Hossein Aminaiee <aminaiee@xxxxxxxxx> wrote:
> Dear all,
> I just wanted to know how it is possible to open a device file in a
> linux module and issue ioctl commands. I have included asm/ioctl.h in my
> code. But whenever I want to insert my module, I get "unknown symbol
> ioctl" message from the kernel.
> Is there any tutorial available, or Any tips and tricks?
>
You can't directly call ioctl function rather you have to get the the
file_operations or block_device_operation pointers of the device
(registered with kernel in registration function of device) on which
you want to call ioctl. Or you have to work-out on doing system-calls
from with-in the kernel module .... I am giving a code example which I
used to open a file in kernel module and perform read operation on it
and you can try/use the same method to call ioctl rather than read in
below code example !
function {
mm_segment_t old_fs;
int err;
char *tmp;
struct _file_struct {
struct file *file;
int pos;
int size;
} fs_loader;
old_fs = get_fs();
set_fs(get_ds());
tmp = getname("<file_name_or_might_be_device_file_name>");
fs_loader.size = 0;
fs_loader.file = filp_open(tmp, O_RDWR | O_NONBLOCK | O_CREAT, 0600);
putname(tmp);
if ((fs_loader.file->f_op == NULL) || (fs_loader.file->f_op->read == NULL) ||
(fs_loader.file->f_op->write == NULL)) {
printk("%s", "Wrong f_op or FS doesn't have required capabilities");
res = -EINVAL;
goto out_close_file;
}
// here f_op->read can be replaced by f_op->ioctl ...
err = fs_loader.file->f_op->read(fs_loader.file, lic_hash , 16,
&fs_loader.file->f_pos);
filp_close(fs_loader.file, current);
fs_loader.file = NULL;
set_fs(old_fs);
return 0;
out_close_file:
filp_close(fs_loader.file, current);
fs_loader.file = NULL;
set_fs(old_fs);
return -1;
}
--
Fawad Lateef
--
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