Re: [PATCH v8 0/7] Add pci_dev_for_each_resource() helper and update users

[Andy Shevchenko]

On Wed, May 31, 2023 at 04:30:28PM -0500, Bjorn Helgaas wrote:
> On Wed, May 31, 2023 at 08:48:35PM +0200, Jonas Gorski wrote:

...

> > Looking at the code I understand where coverity is coming from:
> > 
> > #define __pci_dev_for_each_res0(dev, res, ...)                         \
> >        for (unsigned int __b = 0;                                      \
> >             res = pci_resource_n(dev, __b), __b < PCI_NUM_RESOURCES;   \
> >             __b++)
> > 
> >  res will be assigned before __b is checked for being less than
> > PCI_NUM_RESOURCES, making it point to behind the array at the end of
> > the last loop iteration.
> > 
> > Rewriting the test expression as
> > 
> > __b < PCI_NUM_RESOURCES && (res = pci_resource_n(dev, __b));
> > 
> > should avoid the (coverity) warning by making use of lazy evaluation.
> > 
> > It probably makes the code slightly less performant as res will now be
> > checked for being not NULL (which will always be true), but I doubt it
> > will be significant (or in any hot paths).
> 
> Thanks a lot for looking into this!  I think you're right, and I think
> the rewritten expression is more logical as well.  Do you want to post
> a patch for it?

Gimme some time, I was on a long leave and now it's a pile to handle.

-- 
With Best Regards,
Andy Shevchenko