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SubjectRe: [PATCH] drivercore: Add driver probe deferral mechanism
On Mon, 04 Jul 2011 11:11:59 -0600 Grant Likely wrote:

> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 6658da7..ccbf3d3 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -28,6 +28,62 @@
> #include "base.h"
> #include "power/power.h"
>
> +/**
> + * deferred_probe_work_func() - Retry probing devices in the deferred list.
> + */
> +static DEFINE_MUTEX(deferred_probe_mutex);
> +static LIST_HEAD(deferred_probe_list);
> +static void deferred_probe_work_func(struct work_struct *work)

The kernel-doc notation needs to be immediately before the function,
without the intervening data...

> +{
> + struct device *dev;
> + /*
> + * This bit is tricky. We want to process every device in the
> + * deferred list, but devices can be removed from the list at any
> + * time while inside this for-each loop. There are two things that
> + * need to be protected against:
> + * - if the device is removed from the deferred_probe_list, then we
> + * loose our place in the loop. Since any device can be removed
> + * asynchronously, list_for_each_entry_safe() wouldn't make things
> + * much better. Simplest solution is to restart walking the list
> + * whenever the current device gets removed. Not the most efficient,
> + * but is simple to implement and easy to audit for correctness.
> + * - if the device is unregistered, and freed, then there is a risk
> + * of a null pointer dereference. This code uses get/put_device()
> + * to ensure the device cannot disappear from under our feet.
> + */


---
~Randy
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