> -----Original Message----- > From: Greg KH [mailto:gregkh@xxxxxxxxxxxxxxxxxxx] > Sent: Thursday 6 June 2019 14:29 > 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 V4 04/12] misc: xilinx_sdfec: Add open, close and ioctl > > On Sat, May 25, 2019 at 12:37:17PM +0100, Dragan Cvetic wrote: > > +static int xsdfec_dev_open(struct inode *iptr, struct file *fptr) > > +{ > > + return 0; > > +} > > + > > +static int xsdfec_dev_release(struct inode *iptr, struct file *fptr) > > +{ > > + return 0; > > +} > > empty open/close functions are never needed, just drop them. Accepted. Will remove them. > > > + > > +static long xsdfec_dev_ioctl(struct file *fptr, unsigned int cmd, > > + unsigned long data) > > +{ > > + struct xsdfec_dev *xsdfec; > > + void __user *arg = NULL; > > + int rval = -EINVAL; > > + > > + xsdfec = container_of(fptr->private_data, struct xsdfec_dev, miscdev); > > + if (!xsdfec) > > + return rval; > > It is impossible for container_of() to return NULL, unless something > very magical and rare just happened. It's just doing pointer math, you > can never check the return value of it. Accepted. Will remove if statement. > > > + > > + if (_IOC_TYPE(cmd) != XSDFEC_MAGIC) > > + return -ENOTTY; > > How can this happen? Accepted. Will be removed. > > > + > > + /* check if ioctl argument is present and valid */ > > + if (_IOC_DIR(cmd) != _IOC_NONE) { > > + arg = (void __user *)data; > > + if (!arg) > > + return rval; > > + } > > + > > + switch (cmd) { > > + default: > > + /* Should not get here */ > > + dev_warn(xsdfec->dev, "Undefined SDFEC IOCTL"); > > Nice that userspace has a way to fill up the kernel log :( > > Just return the correct error here, don't log it. Accepted. Will remove log. > > thanks, > > greg k-h
