On Friday, October 02, 2015 09:14:28 AM Tomeu Vizoso wrote:
> Adds a function that tells whether a device is already bound to a
> driver.
>
> This is needed to warn when there is an attempt to change the PM domain
> of a device that has finished probing already. The reason why we want to
> enforce that is because in the general case that can cause problems and
> also that we can simplify code quite a bit if we can always assume that.
>
> Signed-off-by: Tomeu Vizoso <tomeu.viz...@collabora.com>
> ---
>
> Changes in v8:
> - Add device_is_bound()
>
> drivers/base/dd.c | 9 +++++++--
> include/linux/device.h | 2 ++
> 2 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index be0eb4639128..f2007fa7316f 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -192,9 +192,14 @@ static int deferred_probe_initcall(void)
> }
> late_initcall(deferred_probe_initcall);
>
> +bool device_is_bound(struct device *dev)
> +{
> + return klist_node_attached(&dev->p->knode_driver);
> +}
It would be useful here to add a comment explaining what locks need to be held
around this for it to be non-racy IMO.
> +
> static void driver_bound(struct device *dev)
> {
> - if (klist_node_attached(&dev->p->knode_driver)) {
> + if (device_is_bound(dev)) {
> printk(KERN_WARNING "%s: device %s already bound\n",
> __func__, kobject_name(&dev->kobj));
> return;
> @@ -545,7 +550,7 @@ static int __device_attach(struct device *dev, bool
> allow_async)
>
> device_lock(dev);
> if (dev->driver) {
> - if (klist_node_attached(&dev->p->knode_driver)) {
> + if (device_is_bound(dev)) {
> ret = 1;
> goto out_unlock;
> }
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 5d7bc6349930..9b41c05fb479 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -1035,6 +1035,8 @@ extern int __must_check driver_attach(struct
> device_driver *drv);
> extern void device_initial_probe(struct device *dev);
> extern int __must_check device_reprobe(struct device *dev);
>
> +extern bool device_is_bound(struct device *dev);
> +
> /*
> * Easy functions for dynamically creating devices on the fly
> */
>
Thanks,
Rafael
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