Hi Manivannan,
> From: Manivannan Sadhasivam, Sent: Tuesday, June 21, 2022 11:21 PM
>
> On Tue, Jun 21, 2022 at 09:11:47PM +0900, Yoshihiro Shimoda wrote:
> > Add pci_epc_nop_release() for epc->dev.release. Otherwise,
> > WARN() happened when a PCIe endpoint driver is removed.
> >
> > Device 'e65d0000.pcie-ep' does not have a release() function, it is broken and must be fixed. See
> Documentation/core-api/kobject.rst.
> > WARNING: CPU: 0 PID: 139 at drivers/base/core.c:2232 device_release+0x78/0x8c
> >
>
> Hmm... So the core is correctly throwing the warning here but just using a NOP
> release function is not the right solution IMO.
>
> Currently, pci_epc_destroy() is handling all resource release including freeing
> the memory for epc. But I think the "kfree(epc)" should be moved to this
> release callback. Reason is quite obvious. Until the release() callback gets
> called, there would be a "epc" device instance floating around and we should not
> free it until then.
I understood it. Especially, we enable CONFIG_DEBUG_KOBJECT_RELEASE=y, the release()
callback will be called after pci_epc_destroy() exited. So, I'll move "kfree(epc)" to
the release function.
Best regards,
Yoshihiro Shimoda
> Thanks,
> Mani
>
> > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
> > ---
> > drivers/pci/endpoint/pci-epc-core.c | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
> > index 3bc9273d0a08..cb533821b072 100644
> > --- a/drivers/pci/endpoint/pci-epc-core.c
> > +++ b/drivers/pci/endpoint/pci-epc-core.c
> > @@ -746,6 +746,10 @@ void devm_pci_epc_destroy(struct device *dev, struct pci_epc *epc)
> > }
> > EXPORT_SYMBOL_GPL(devm_pci_epc_destroy);
> >
> > +static void pci_epc_nop_release(struct device *dev)
> > +{
> > +}
> > +
> > /**
> > * __pci_epc_create() - create a new endpoint controller (EPC) device
> > * @dev: device that is creating the new EPC
> > @@ -779,6 +783,7 @@ __pci_epc_create(struct device *dev, const struct pci_epc_ops *ops,
> > device_initialize(&epc->dev);
> > epc->dev.class = pci_epc_class;
> > epc->dev.parent = dev;
> > + epc->dev.release = pci_epc_nop_release;
> > epc->ops = ops;
> >
> > ret = dev_set_name(&epc->dev, "%s", dev_name(dev));
> > --
> > 2.25.1
> >
>
> --
> மணிவண்ணன் சதாசிவம்
