Re: [Outreachy kernel] [PATCH v2] Staging: emxx_udc: Make a read-only structure

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Oct 19, 2016 at 09:18:29AM +0300, Muraru Mihaela wrote:
> On Wed, Oct 19, 2016 at 08:01:40AM +0200, Julia Lawall wrote:
> > 
> > 
> > On Wed, 19 Oct 2016, Muraru Mihaela wrote:
> > 
> > > On Tue, Oct 18, 2016 at 10:48:54PM +0200, Julia Lawall wrote:
> > > > On Tue, 18 Oct 2016, Mihaela Muraru wrote:
> > > >
> > > > > This patch add const qualifier at the declaration of the structure,
> > > > > because it contains information about usb hardware device and those
> > > > > values shoud not be overwritten.
> > > >
> > > > This focuses on the intent, which makes sense, but one really wants to be
> > > > sure that we won't end up with a const value floating into a modification
> > > > context, which would cause a runtime error.  So it would be good to
> > > > describe how the structure is used.  For example, is it only passed to
> > > > another function where the corresponding parameter is declared as const?
> > >
> > > The structure is declared and used only in emxx_udc.c. I searched it in all
> > > staging driver.
> > >
> > > And is passed as a patameter only to the sizeof operetor,
> > > that doesn't change the variable of the structure.
> > >
> > > To be 100% sure I will search on all the files of the kernel,
> > > it would take some time, and I will tell you what is the result, if is
> > > ok for you.
> > 
> > If the structure is static, then there is normally no need to check other
> > files.  The question though is how is it used in the current file.  Sizeof
> > is indeed not an issue, but what are the other ways in which it is used.
> 
> As I mentioned  it is not used in the current file. Now, I am
> wondering why is declared.

Yes, that is odd, does the compiler give you a warning about it when you
build the code that it's not being used?

thanks,

greg k-h