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SubjectRe: [PATCH] devres: WARN() and return, don't crash on device_del() of uninitialized device
On Mon, 25 May 2009 16:53:31 +1000
Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:

> I just debugged an obscure crash caused by a device_del() of a all NULL'd
> out struct device (in usb-serial) and found that a patch like this one would
> have saved me time (in addition to improved chances of a bug report from
> users hitting similar driver bugs).
>
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> ---
>
> drivers/base/devres.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> --- linux-work.orig/drivers/base/devres.c 2009-05-25 16:43:46.000000000 +1000
> +++ linux-work/drivers/base/devres.c 2009-05-25 16:46:36.000000000 +1000
> @@ -428,6 +428,11 @@ int devres_release_all(struct device *de
> {
> unsigned long flags;
>
> + /* Looks like an uninitialized device structure */
> + if (dev->devres_head.next == NULL) {
> + WARN(1);
> + return -ENODEV;
> + }
> spin_lock_irqsave(&dev->devres_lock, flags);
> return release_nodes(dev, dev->devres_head.next, &dev->devres_head,
> flags);

This could be coded a little more neatly as:

/* Looks like an uninitialized device structure */
if (WARN_ON(dev->devres_head.next == NULL))
return -ENODEV;



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