> On Thu, Jan 18, 2018 at 12:35:25PM -0600, Bjorn Helgaas wrote:
> > On Thu, Jan 18, 2018 at 03:54:20PM +0100, Ladislav Michl wrote:
> > > On Thu, Jan 18, 2018 at 02:00:37PM +0000, Wei Yongjun wrote:
> > > > platform_get_resource_byname() may fail and return NULL, so we
> should
> > > > better check it's return value to avoid a NULL pointer dereference a
> > > > bit later in the code.
> > > >
> > > > This is detected by Coccinelle semantic patch.
> > > >
> > > > @@
> > > > expression pdev, res, n, t, e, e1, e2;
> > > > @@
> > > >
> > > > res = platform_get_resource_byname(pdev, t, n);
> > > > + if (!res)
> > > > + return -EINVAL;
> > > > ... when != res == NULL
> > > > e = devm_ioremap(e1, res->start, e2);
> > >
> > > Well, then it should be replaced with devm_ioremap_resource()
> > > which already checks for NULL and the right resource type
> > > (IORESOURCE_MEM).
> >
> > That's probably a better idea. Maybe we should add a comment like this
> > to help avoid this in the future:
Not all of the place using devm_ioremap() can be replaced with
devm_ioremap_resource(), devices share the memory resource for example.
So maybe you should also add an exception list to the comment, otherwise
many people still not know how to use devm_ioremap_resource() or devm_ioremap().
> >
> > --- a/lib/devres.c
> > +++ b/lib/devres.c
> > @@ -22,6 +22,8 @@ static int devm_ioremap_match(struct device *dev,
> void *res, void *match_data)
> > * @size: Size of map
> > *
> > * Managed ioremap(). Map is automatically unmapped on driver detach.
> > + *
> > + * When possible, use devm_ioremap_resource() instead.
> > */
> > void __iomem *devm_ioremap(struct device *dev, resource_size_t offset,
> > resource_size_t size)
>
> Yes, please. It would be nice first patch in the serie converting existing
> users of devm_ioremap into devm_ioremap_resource:
> find drivers -name "*.c" | xargs grep "devm_ioremap(" | grep resource_size
> | wc -l
> 82
> I know, that was dumb, Coccinelle would certainly do better job.
> And from a quick look a lot of
> if (!res) {
> print error
> return -EINVAL;
> }
> code blocks could be deleted (and many cases where check for NULL
> resource
> is missing fixed).
>
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