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SubjectRe: [linux-pm] [PATCH 2/9] PM: suspend_block: Add driver to access suspend blockers from user-space
On Mon, 26 Apr 2010, Arve Hjønnevåg wrote:

> > If you insist on using ioctl for init, you should use the standard
> > convention for passing variable-length data.  The userspace program
> > sets up a fixed-size buffer containing a pointer to the name and the
> > name's length, and it passes the buffer's address as the ioctl
> > argument.
>
> Are you sure that is the standard? I searched for ioctls with NAME in
> their name and only found one that passed the name that way. The rest
> used fixed length string buffers, or passed the buffersize to _IOC
> like I do. For instance, input.h has ioctls to read string and
> bitmasks where user space specify the buffer size as an argument to
> the ioctl macro. These pass data from the kernel to user space, but I
> don't passing a string length is any worse than passing a buffer size.

You're right. Okay, I withdraw my objection.

Alan Stern

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