Re: [PATCH V3 04/12] misc: xilinx_sdfec: Add open, close and ioctl

[Greg KH]

On Fri, May 03, 2019 at 04:44:57PM +0000, Dragan Cvetic wrote:
> > -----Original Message-----
> > From: Greg KH [mailto:gregkh@xxxxxxxxxxxxxxxxxxx]
> > Sent: Thursday 2 May 2019 18:23
> > To: Dragan Cvetic <draganc@xxxxxxxxxx>
> > Cc: arnd@xxxxxxxx; Michal Simek <michals@xxxxxxxxxx>; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; robh+dt@xxxxxxxxxx;
> > mark.rutland@xxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Derek Kiernan <dkiernan@xxxxxxxxxx>
> > Subject: Re: [PATCH V3 04/12] misc: xilinx_sdfec: Add open, close and ioctl
> > 
> > On Sat, Apr 27, 2019 at 11:04:58PM +0100, Dragan Cvetic wrote:
> > > +static int xsdfec_dev_open(struct inode *iptr, struct file *fptr)
> > > +{
> > > +	struct xsdfec_dev *xsdfec;
> > > +
> > > +	xsdfec = container_of(iptr->i_cdev, struct xsdfec_dev, xsdfec_cdev);
> > > +
> > > +	if (!atomic_dec_and_test(&xsdfec->open_count)) {
> > 
> > Why do you care about this?
> > 
> > And do you really think it matters?  What are you trying to protect from
> > here?
> 
> There is a request to increase the driver security. 

How does this affect "security" in any way?

> It is acceptable for us for now, even with non-perfections (will not
> be protected if opened twice with dup() or fork()).  This is covered
> in the documentation.

As this really "does nothing", no need to bother the kernel with trying
to keep this logic working properly.  So please just drop it.

thanks,

greg k-h