Hi,
On 06/18/2012 08:34 PM, Pritam Bankar wrote:
> Hi,
> I have one structure called foo. Address of object of foo(say objfoo) is
> passed to ioctl call
>
> status = ioctl(fd, arg, &objfoo);
as objfoo is a pointer to foo:
struct something foo;
struct somethint *objfoo = &foo;
&objfoo therefore is a pointer to a pointer, not sure if you wanted to
pass this to the ioctl.
>
> But during manipulation I am not getting ioctl error 5 (input/output error).
> I am more confused about error in dmesg which is
> *foo: no-op *
you can't work directly on a object in userspace memory as this might be
a security issue. There exits a function to copy from user memory area
to kernel memory area (copy_from_user; and afterwards copy back to the
user; copy_to_user).
Cheers,
Matthias
>
> What does no-op indicate? If it is no-operation, how can we relate this
> to foo structure?
>
> Thanks,
> Pritam
>
>
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