Re: [PATCH v2 1/7] device core: add BUS_NOTIFY_BIND_DRIVER_ERROR notification

Rafael J. Wysocki
2015-11-26T22:39:30Z

On Thursday, November 26, 2015 05:19:07 PM Andy Shevchenko wrote:
> In case ->probe() fails the notifier does not inform a subscriber about this.
> In the result it might happend that some resources that had been allocated will
> stay allocated and therefore lead to resource leak.
>
> Introduce a new notification to inform the subscriber that ->probe() failed.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

I'd rather say the problem is that the users of BUS_NOTIFY_BIND_DRIVER have no
chance to do any cleanup in case of a probe failure (there may be problems even
if resources aren't leaked).

> ---
> drivers/base/dd.c | 8 ++++++--
> include/linux/device.h | 1 +
> 2 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index a641cf3..ac071a5 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -290,7 +290,7 @@ static int really_probe(struct device *dev, struct device_driver *drv)
> /* If using pinctrl, bind pins now before probing */
> ret = pinctrl_bind_pins(dev);
> if (ret)
> - goto probe_failed;
> + goto pinctrl_bind_failed;
>
> if (driver_sysfs_add(dev)) {
> printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
> @@ -334,6 +334,11 @@ static int really_probe(struct device *dev, struct device_driver *drv)
> goto done;
>
> probe_failed:
> + if (dev->bus)
> + blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
> + BUS_NOTIFY_BIND_DRIVER_ERROR,
> + dev);

Well, if we do that, device_bind_driver() needs to send that notification too
in case it doesn't call driver_bound().

> +pinctrl_bind_failed:
> devres_release_all(dev);
> driver_sysfs_remove(dev);
> dev->driver = NULL;
> @@ -701,7 +706,6 @@ static void __device_release_driver(struct device *dev)
> blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
> BUS_NOTIFY_UNBOUND_DRIVER,
> dev);
> -
> }
> }
>
> diff --git a/include/linux/device.h b/include/linux/device.h
> index b8f411b..87cf423 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -191,6 +191,7 @@ extern int bus_unregister_notifier(struct bus_type *bus,
> unbound */
> #define BUS_NOTIFY_UNBOUND_DRIVER 0x00000007 /* driver is unbound
> from the device */
> +#define BUS_NOTIFY_BIND_DRIVER_ERROR 0x80000004 /* driver fails to be bound */

I'd call it BUS_NOTIFY_DRIVER_NOT_BOUND.

>
> extern struct kset *bus_get_kset(struct bus_type *bus);
> extern struct klist *bus_get_device_klist(struct bus_type *bus);
>

Thanks,
Rafael