Messages in this thread | | | From | Dragan Cvetic <> | Subject | RE: [PATCH V4 04/12] misc: xilinx_sdfec: Add open, close and ioctl | Date | Thu, 6 Jun 2019 18:22:07 +0000 |
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> -----Original Message----- > From: Greg KH [mailto:gregkh@linuxfoundation.org] > Sent: Thursday 6 June 2019 14:29 > To: Dragan Cvetic <draganc@xilinx.com> > Cc: arnd@arndb.de; Michal Simek <michals@xilinx.com>; linux-arm-kernel@lists.infradead.org; robh+dt@kernel.org; > mark.rutland@arm.com; devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; Derek Kiernan <dkiernan@xilinx.com> > 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
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