On Thu, Mar 23, 2023 at 10:22 PM Uwe Kleine-König
<u.kleine-koenig@xxxxxxxxxxxxxx> wrote:
>
> Hello Pierre,
>
> On Tue, Mar 07, 2023 at 09:08:55PM +0100, Uwe Kleine-König wrote:
> > On Tue, Mar 07, 2023 at 02:31:49PM -0500, Pierre Asselin wrote:
> > > > Maybe the following patch helps (on top of v6.3-rc1):
> > > >
> > > > diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> > > > index 9531dd0fef50..a5a8f82981ce 100644
> > > > --- a/drivers/acpi/bus.c
> > > > +++ b/drivers/acpi/bus.c
> > > > @@ -518,7 +518,7 @@ static void acpi_bus_notify(acpi_handle handle, u32
> > > > type, void *data)
> > > > if (!adev)
> > > > goto err;
> > > >
> > > > - if (adev->dev.driver) {
> > > > + if (device_is_bound(&adev->dev)) {
> > > > struct acpi_driver *driver = to_acpi_driver(adev->dev.driver);
> > > >
> > > > if (driver && driver->ops.notify &&
> > > >
> > >
> > > It does indeed "fix" 6.3-rc1. Modulo locking issues, which I am
> > > not qualified to evaluate.
> >
> > Thanks for your prompt test feedback.
> >
> > The locked variant could look as follows:
> >
> > diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> > index 9531dd0fef50..fddca263ac40 100644
> > --- a/drivers/acpi/bus.c
> > +++ b/drivers/acpi/bus.c
> > @@ -518,13 +518,15 @@ static void acpi_bus_notify(acpi_handle handle, u32 type, void *data)
> > if (!adev)
> > goto err;
> >
> > - if (adev->dev.driver) {
> > + device_lock(&adev->dev);
> > + if (device_is_bound(&adev->dev)) {
> > struct acpi_driver *driver = to_acpi_driver(adev->dev.driver);
> >
> > if (driver && driver->ops.notify &&
> > (driver->flags & ACPI_DRIVER_ALL_NOTIFY_EVENTS))
> > driver->ops.notify(adev, type);
> > }
> > + device_unlock(&adev->dev);
> >
> > if (!hotplug_event) {
> > acpi_put_acpi_dev(adev);
> >
> > Pierre: If you want to test that, I suggest to also enable
> > PROVE_LOCKING.
> >
> > Rafael: I don't know if this would work and I hope you're able to judge
> > this better than I do. The change without the lock is for sure better
> > than the status quo.
> >
> > I did a similar conversion as the blamed commit for pci that got
> > reverted for similiar reasons. See
> > 68da4e0eaaab421f228eac57cbe7505b136464af. (Added Bjorn and Robert to
> > Cc:) I think the pci code suffers from a similar race even after
> > reverting my change. If someone is able to find the right fix for one of
> > them, that might be transferable to the other?!
>
> This mail didn't make it into the archive on lore.kernel.org. Did
> someone receive it?
I have received it.
