Re: [PATCH] driver core: Move device_links_purge() after bus_remove_device()

From: Rafael J. Wysocki
Date: Wed Oct 18 2017 - 19:46:11 EST


On Wednesday, October 18, 2017 1:28:38 PM CEST Jeffy Chen wrote:
> Currently we are unbinding device link consumers when detaching the
> supplier. So we need to make sure the detaching happens before purging
> the supplier's device links.
>
> Move device_links_purge() after bus_remove_device() in device_del()
> for that.
>
> Signed-off-by: Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx>

Yes, we can do that, but the changelog is somewhat hard to understand IMO.

Why don't you write something like the following:

"The current ordering of code in device_del() triggers a WARN_ON()
in device_links_purge(), because of an unexpected link status.

The device_links_unbind_consumers() call in device_release_driver()
has to take place before device_links_purge() for the status of all
links to be correct, so move the device_links_purge() call in
device_del() after the invocation of bus_remove_device() which calls
device_release_driver()."

> ---
>
> drivers/base/core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 12ebd055724c..2e683cdf4a08 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -1958,7 +1958,6 @@ void device_del(struct device *dev)
> blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
> BUS_NOTIFY_DEL_DEVICE, dev);
>
> - device_links_purge(dev);
> dpm_sysfs_remove(dev);
> if (parent)
> klist_del(&dev->p->knode_parent);
> @@ -1986,6 +1985,7 @@ void device_del(struct device *dev)
> device_pm_remove(dev);
> driver_deferred_probe_del(dev);
> device_remove_properties(dev);
> + device_links_purge(dev);
>
> /* Notify the platform of the removal, in case they
> * need to do anything...
>