Messages in this thread | | | Date | Sat, 24 May 2008 00:43:59 +0200 | From | "Hans J. Koch" <> | Subject | Re: [PATCH 1/1] UIO: Add a write() function to enable/disable interrupts |
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On Fri, May 23, 2008 at 10:44:42PM +0200, Leon Woestenberg wrote: > Hello, > > On Fri, May 23, 2008 at 1:55 PM, Hans J. Koch <hjk@linutronix.de> wrote: > > +static ssize_t uio_write(struct file *filep, const char __user *buf, > > + size_t count, loff_t *ppos) > > +{ > > + struct uio_listener *listener = filep->private_data; > > + struct uio_device *idev = listener->dev; > > + ssize_t retval; > > + s32 irq_on; > > + > > + if (idev->info->irq == UIO_IRQ_NONE) > > + return -EIO; > > + > > + if (count != sizeof(s32)) > > + return -EINVAL; > > + > > + if (!idev->info->irqcontrol) > > + return -ENOSYS; > > + > > + if (copy_from_user(&irq_on, buf, count)) > > + return -EFAULT; > > + > > + retval = idev->info->irqcontrol(idev->info, irq_on); > > + > > + return retval ? retval : sizeof(s32); > > +} > > + > > Shouldn't this be more future-proof, what if we need to abuse write() > for something else in the future?
We don't. I'm thinking about letting the function fail if irq_on is not 0 or 1, just to stop any ideas of abusing write().
read() and write() only deal with irq handling, all data exchange with the device is done through mapped memory.
> > I would suggest a check for ppos to be 0 (zero) as well, just to be > sure and future-proof and backwards-safe.
write() is only for enabling/disabling irqs, there's only one possible value of count, and we don't have a seek function. So why check ppos?
Thanks, Hans
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