3.12-stable review patch. If anyone has any objections, please let me know.
------------------ From: Mauro Carvalho Chehab <[email protected]> commit 24e9a47e14f0a97ee97abc3dd86b2ef254448a17 upstream. 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]> Reviewed-by: Hans Verkuil <[email protected]> Signed-off-by: Mauro Carvalho Chehab <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/media/v4l2-core/v4l2-async.c | 30 +++++++++++++++++++++++++++--- 1 file changed, 27 insertions(+), 3 deletions(-) --- a/drivers/media/v4l2-core/v4l2-async.c +++ b/drivers/media/v4l2-core/v4l2-async.c @@ -189,30 +189,53 @@ void v4l2_async_notifier_unregister(stru 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(n_subdev * sizeof(*dev), GFP_KERNEL); + if (!dev) { + dev_err(notifier->v4l2_dev->dev, + "Failed to allocate device cache!\n"); + } + mutex_lock(&list_lock); list_del(¬ifier->list); list_for_each_entry_safe(sd, tmp, ¬ifier->done, async_list) { - dev[i] = get_device(sd->dev); + struct device *d; + + d = get_device(sd->dev); v4l2_async_cleanup(sd); /* If we handled USB devices, we'd have to lock the parent too */ - device_release_driver(dev[i++]); + device_release_driver(d); if (notifier->unbind) notifier->unbind(notifier, sd, sd->asd); + + /* + * Store device at the device cache, in order to call + * put_device() on the final step + */ + if (dev) + dev[i++] = d; + else + put_device(d); } mutex_unlock(&list_lock); + /* + * Call device_attach() to reprobe devices + * + * NOTE: If dev allocation fails, i is 0, and the whole loop won't be + * executed. + */ while (i--) { struct device *d = dev[i]; @@ -228,6 +251,7 @@ void v4l2_async_notifier_unregister(stru } put_device(d); } + kfree(dev); notifier->v4l2_dev = NULL; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
