Hi Greg, Please find inline comments below. Regards Dragan > -----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. 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. > > > + atomic_inc(&xsdfec->open_count); > > + return -EBUSY; > > + } > > + > > + fptr->private_data = xsdfec; > > + return 0; > > +} > > + > > +static int xsdfec_dev_release(struct inode *iptr, struct file *fptr) > > +{ > > + struct xsdfec_dev *xsdfec; > > + > > + xsdfec = container_of(iptr->i_cdev, struct xsdfec_dev, xsdfec_cdev); > > + > > + atomic_inc(&xsdfec->open_count); > > You increment a number when the device is closed? > > You are trying to make it hard to maintain this code over time :) > > > > + return 0; > > +} > > + > > +static long xsdfec_dev_ioctl(struct file *fptr, unsigned int cmd, > > + unsigned long data) > > +{ > > + struct xsdfec_dev *xsdfec = fptr->private_data; > > + void __user *arg = NULL; > > + int rval = -EINVAL; > > + int err = 0; > > + > > + if (!xsdfec) > > + return rval; > > + > > + if (_IOC_TYPE(cmd) != XSDFEC_MAGIC) > > + return -ENOTTY; > > + > > + /* check if ioctl argument is present and valid */ > > + if (_IOC_DIR(cmd) != _IOC_NONE) { > > + arg = (void __user *)data; > > + if (!arg) { > > + dev_err(xsdfec->dev, > > + "xilinx sdfec ioctl argument is NULL Pointer"); > > You just created a way for userspace to spam the kernel log, please do > not do that :( Will be removed. > > > > > + return rval; > > + } > > + } > > + > > + if (err) { > > + dev_err(xsdfec->dev, "Invalid xilinx sdfec ioctl argument"); > > + return -EFAULT; > > Wrong error, you did not have a memory fault. Absolutely useless code. Will be removed. Thanks. > > Again, you just created a way to spam the kernel log by a user :( > > thanks, > > greg k-h
