On 11/02/2013 02:31 PM, Mauro Carvalho Chehab wrote:
> Dynamic static allocation is evil, as Kernel stack is too low, and
> compilation complains about it on some archs:
>
> drivers/media/v4l2-core/v4l2-async.c:238:1: warning:
> 'v4l2_async_notifier_unregister' uses dynamic stack allocation [enabled by
> default]
>
> Instead, let's enforce a limit for the buffer.
>
> In this specific case, there's a hard limit imposed by V4L2_MAX_SUBDEVS,
> with is currently 128. That means that the buffer size can be up to
> 128x8 = 1024 bytes (on a 64bits kernel), with is too big for stack.
>
> Worse than that, someone could increase it and cause real troubles.
>
> So, let's use dynamically allocated data, instead.
>
> Signed-off-by: Mauro Carvalho Chehab <[email protected]>
> Cc: Guennadi Liakhovetski <[email protected]>
> ---
> drivers/media/v4l2-core/v4l2-async.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-async.c
> b/drivers/media/v4l2-core/v4l2-async.c
> index c85d69da35bd..071596869036 100644
> --- a/drivers/media/v4l2-core/v4l2-async.c
> +++ b/drivers/media/v4l2-core/v4l2-async.c
> @@ -189,12 +189,14 @@ void v4l2_async_notifier_unregister(struct
> v4l2_async_notifier *notifier)
> struct v4l2_subdev *sd, *tmp;
> unsigned int notif_n_subdev = notifier->num_subdevs;
> unsigned int n_subdev = min(notif_n_subdev, V4L2_MAX_SUBDEVS);
> - struct device *dev[n_subdev];
> + struct device **dev;
> int i = 0;
>
> if (!notifier->v4l2_dev)
> return;
>
> + dev = kmalloc(sizeof(*dev) * n_subdev, GFP_KERNEL);
> +
No check for dev == NULL?
Regards,
Hans
> mutex_lock(&list_lock);
>
> list_del(¬ifier->list);
> @@ -228,6 +230,7 @@ void v4l2_async_notifier_unregister(struct
> v4l2_async_notifier *notifier)
> }
> put_device(d);
> }
> + kfree(dev);
>
> notifier->v4l2_dev = NULL;
>
>
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