Re: [bug report] PCI: endpoint: Automatically create a function specific attributes group

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Sun, May 14, 2023 at 11:12:22PM +0300, Dan Carpenter wrote:
> On Sun, May 14, 2023 at 07:06:52PM +0530, Manivannan Sadhasivam wrote:
> > On Thu, May 11, 2023 at 10:06:40AM +0300, Dan Carpenter wrote:
> > > Hello Damien Le Moal,
> > > 
> > > The patch 01c68988addf: "PCI: endpoint: Automatically create a
> > > function specific attributes group" from Apr 15, 2023, leads to the
> > > following Smatch static checker warning:
> > > 
> > > 	drivers/pci/endpoint/pci-ep-cfs.c:540 pci_ep_cfs_add_type_group()
> > > 	warn: 'group' isn't an ERR_PTR
> > > 
> > > drivers/pci/endpoint/pci-ep-cfs.c
> > >     532 static void pci_ep_cfs_add_type_group(struct pci_epf_group *epf_group)
> > >     533 {
> > >     534         struct config_group *group;
> > >     535 
> > >     536         group = pci_epf_type_add_cfs(epf_group->epf, &epf_group->group);
> > >     537         if (!group)
> > >     538                 return;
> > >     539 
> > > --> 540         if (IS_ERR(group)) {
> > > 
> > > pci_epf_type_add_cfs() does not return error pointers currently.  Which
> > > is fine.  Presumably it will start returning them later.  But could you
> > > add some comments next to the pci_epf_type_add_cfs() to explain what a
> > > NULL return means vs an error pointer return?
> > > 
> > 
> > pci_epf_type_add_cfs() may return ERR_PTR from add_cfs() callback.
> > 
> 
> Right, we presumably will add new implementations of ->add_cfs in the
> future which return error pointers.  Currently in linux-next there are
> only two and neither of them fail.  (Smatch looks at the returns from
> ->add_cfs when it says that these don't return error pointers.  Of
> course, it depends on your .config as well.  But a quick grep confirms
> that both implementations are included in my ARM allmodconfig).
> 

Ah okay. I never thought Smatch would look into callback definitions. Good to
know!

- Mani

> > Regarding comments, it should be added as a part of kdoc for
> > pci_epf_type_add_cfs(). It already does for NULL part but not for ERR_PTR.
> 
> Excelent thanks.
> 
> regards,
> dan carpenter
> 

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