On Sat, 20 Aug 2005, Christoph Hellwig wrote:
> > +config EXTINT_SGI_IOC4
> > + tristate "Device driver for SGI IOC4 external interrupts"
> > + depends on (IA64_GENERIC || IA64_SGI_SN2) && EXTINT && BLK_DEV_SGIIOC4
>
> Is the ioc4 core abstraction config symbol really BLK_DEV_SGIIOC4?
> That probably wants fixing in a separate patch.
Oops. Yes, in the past BLK_DEV_SGIIOC4 was the core abstraction config
symbol. That was fixed a release or two ago, but obviously I've been
working on the external interrupt stuff for a while. Fixed.
> > + This option enables support for the external interrupt ingest
> > + and generation capabilities of SGI IOC4 IO controllers. If
> > + you have an SGI Altix with an IOC4 based IO card, say Y.
> > + Otherwise, say N.
>
> Is there any Altix without an ioc4?
Yes, the Altix 330 uses third-party chips to provide base I/O functions.
Other future Altix products will similarly lack IOC4 (at least in their
base configuration).
> > +static ssize_t ioc4_extint_get_modelist(struct extint_device *ed, char *buf) {
>
> opening brace on a separate line please.
Sorry. Lindent took to mungeing my source (indenting in structure
definitions in particular) in unreadable ways, so I stopped using it.
Old coding styles die hard and all.
> > +#if PAGE_SIZE <= IOC4_A_INT_OUT_LENGTH
> > + /* Only set up INT_OUT register alias page if the system page size
> > + * is equal to or less than the register alias page size. Otherwise
> > + * the user would have access to registers other than INT_OUT.
> > + */
> > + a_int_out = pci_resource_start(ied->idd->idd_pdev, 0) +
> > + IOC4_A_INT_OUT_OFFSET;
> > + if (!a_int_out) {
> > + printk(KERN_WARNING
> > + "%s: Unable to get IOC4 int_out alias mapping "
> > + "for pci_dev 0x%p.\n", __FUNCTION__, ied->idd->idd_pdev);
> > + goto skip_alias;
> > + }
> > + if (!request_region(a_int_out, IOC4_A_INT_OUT_LENGTH,
> > + "ioc4_a_int_out")) {
>
> This looks rather bad. So the driver silently has less functionality
> when using a bigger page size?
For security correctness we cannot allow this page to be mapped by
anything larger than a 16K page, as that would allow the user access
to control registers which are not harmless if exposed.
However, the loss of functionality isn't silent. In ioc4_extint_mmap()
we return -ENXIO if the mapping cannot be performed for the aforementioned
reason. A well-written application will check for failures from mmap(2).
> > +static int ioc4_extint_remove(struct ioc4_driver_data *idd)
> > +{
> > + struct extint_device *ed = idd->idd_extint_data;
> > + struct ioc4_extint_device *ied;
> > +
> > + /* If probe failed, avoid trying to remove */
> > + if (ed)
> > + ied = extint_get_devdata(ed);
> > + else
> > + return -ENXIO;
>
> This should at lease be written:
>
> if (!ed)
> return -ENXIO;
> ied = extint_get_devdata(ed);
>
> but I don't understand how it can happen anyway. ->remove shoould
> never be called unless ->probe initialized the device fully and
> returned 0
It was just one of many things where I coded defensively and intended
to revisit it later. Unfortunately the revisit never took place.
Thanks for the catch -- fixed now.
Thanks,
Brent
--
Brent Casavant If you had nothing to fear,
[email protected] how then could you be brave?
Silicon Graphics, Inc. -- Queen Dama, Source Wars
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