On Fri, Jun 13, 2025 at 3:48 PM Herve Codina <herve.codina@xxxxxxxxxxx> wrote: > > During driver removal, the following warning can appear: > WARNING: CPU: 1 PID: 139 at drivers/base/core.c:1497 __device_links_no_driver+0xcc/0xfc > ... > Call trace: > __device_links_no_driver+0xcc/0xfc (P) > device_links_driver_cleanup+0xa8/0xf0 > device_release_driver_internal+0x208/0x23c > device_links_unbind_consumers+0xe0/0x108 > device_release_driver_internal+0xec/0x23c > device_links_unbind_consumers+0xe0/0x108 > device_release_driver_internal+0xec/0x23c > device_links_unbind_consumers+0xe0/0x108 > device_release_driver_internal+0xec/0x23c > driver_detach+0xa0/0x12c > bus_remove_driver+0x6c/0xbc > driver_unregister+0x30/0x60 > pci_unregister_driver+0x20/0x9c > lan966x_pci_driver_exit+0x18/0xa90 [lan966x_pci] > > This warning is triggered when a consumer is removed because the links > status of its supplier is not DL_DEV_DRIVER_BOUND and the link flag > DL_FLAG_SYNC_STATE_ONLY is not set. > > The topology in terms of consumers/suppliers used was the following > (consumer ---> supplier): > > i2c -----------> OIC ----> PCI device > | ^ > | | > +---> pinctrl ---+ > > When the PCI device is removed, the OIC (interrupt controller) has to be > removed. In order to remove the OIC, pinctrl and i2c need to be removed > and to remove pinctrl, i2c need to be removed. The removal order is: > 1) i2c > 2) pinctrl > 3) OIC > 4) PCI device > > In details, the removal sequence is the following (with 0000:01:00.0 the > PCI device): > driver_detach: call device_release_driver_internal(0000:01:00.0)... > device_links_busy(0000:01:00.0): > links->status = DL_DEV_UNBINDING > device_links_unbind_consumers(0000:01:00.0): > 0000:01:00.0--oic link->status = DL_STATE_SUPPLIER_UNBIND > call device_release_driver_internal(oic)... > device_links_busy(oic): > links->status = DL_DEV_UNBINDING > device_links_unbind_consumers(oic): > oic--pinctrl link->status = DL_STATE_SUPPLIER_UNBIND > call device_release_driver_internal(pinctrl)... > device_links_busy(pinctrl): > links->status = DL_DEV_UNBINDING > device_links_unbind_consumers(pinctrl): > pinctrl--i2c link->status = DL_STATE_SUPPLIER_UNBIND > call device_release_driver_internal(i2c)... > device_links_busy(i2c): links->status = DL_DEV_UNBINDING > __device_links_no_driver(i2c)... > pinctrl--i2c link->status is DL_STATE_SUPPLIER_UNBIND > oic--i2c link->status is DL_STATE_ACTIVE > oic--i2c link->supplier->links.status is DL_DEV_UNBINDING > > The warning is triggered by the i2c removal because the OIC (supplier) > links status is not DL_DEV_DRIVER_BOUND. Its links status is indeed set > to DL_DEV_UNBINDING. > > It is perfectly legit to have the links status set to DL_DEV_UNBINDING > in that case. Indeed we had started to unbind the OIC which triggered > the consumer unbinding and didn't finish yet when the i2c is unbound. > > Avoid the warning when the supplier links status is set to > DL_DEV_UNBINDING and thus support this removal sequence without any > warnings. > > Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx> The change is OK, so Reviewed-by: Rafael J. Wysocki <rafael@xxxxxxxxxx> but it will clash with https://lore.kernel.org/linux-pm/2793309.mvXUDI8C0e@xxxxxxxxxxxxx/ that's been queued up by Greg AFAICS. > --- > drivers/base/core.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/base/core.c b/drivers/base/core.c > index 8fead097c404..ce367c44f642 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -1494,7 +1494,8 @@ static void __device_links_no_driver(struct device *dev) > if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) { > WRITE_ONCE(link->status, DL_STATE_AVAILABLE); > } else { > - WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY)); > + WARN_ON(link->supplier->links.status != DL_DEV_UNBINDING && > + !(link->flags & DL_FLAG_SYNC_STATE_ONLY)); > WRITE_ONCE(link->status, DL_STATE_DORMANT); > } > } > -- > 2.49.0 >
