Hello,
On Tue, Jul 22, 2014 at 12:50:02PM -0600, Bjorn Helgaas wrote:
> [+cc Tejun, LKML]
>
> On Fri, Jul 11, 2014 at 09:08:24AM +0200, Thierry Reding wrote:
> > From: Thierry Reding <[email protected]>
> >
> > Provide device-managed implementations of the request_resource() and
> > release_resource() functions. Upon failure to request a resource, the
> > new devm_request_resource() function will output an error message for
> > consistent error reporting.
> >
> > Signed-off-by: Thierry Reding <[email protected]>
>
> This seems OK to me, but I don't consider myself a devres maintainer. I
> added Tejun and LKML for any comment. Minor nit below.
If there are gonna be users of the interface, sure.
> > +int devm_request_resource(struct device *dev, struct resource *root,
> > + struct resource *new)
> > +{
> > + struct resource *conflict, **ptr;
> > +
> > + ptr = devres_alloc(devm_resource_release, sizeof(*ptr), GFP_KERNEL);
> > + if (!ptr)
> > + return -ENOMEM;
> > +
> > + *ptr = new;
> > +
> > + conflict = request_resource_conflict(root, new);
> > + if (!conflict) {
> > + devres_add(dev, ptr);
> > + return 0;
> > + }
> > +
> > + dev_err(dev, "resource collision: %pR conflicts with %s %pR\n", new,
> > + conflict->name, conflict);
> > + devres_free(ptr);
> > + return -EBUSY;
>
> Personally I would write this as:
>
> conflict = request_resource_conflict(...);
> if (conflict) {
> dev_err(...);
> devres_free(...);
> return -EBUSY;
> }
>
> devres_add(...);
> return 0;
>
> so the straight-line path is the normal, non-error path and errors are
> detected and dealt with in the "if" bodies. Right now the "if" bodies
> are a mix of error handling and normal path. But that's just my personal
> preference.
Agreed.
> > +static int devm_resource_match(struct device *dev, void *res, void *data)
> > +{
> > + struct resource **ptr = res;
> > +
> > + if (WARN_ON(!ptr || !*ptr))
> > + return 0;
How would !ptr or !*ptr possibly happen? Wouldn't that be a bug
already?
Thanks.
--
tejun
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