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SubjectRe: [RFC PATCH v4 12/13] memory-hotplug : add node_device_release
At 07/18/2012 06:17 PM, Yasuaki Ishimatsu Wrote:
> When calling unregister_node(), the function shows following message at
> device_release().
>
> Device 'node2' does not have a release() function, it is broken and must be
> fixed.
>
> So the patch implements node_device_release()
>
> CC: David Rientjes <rientjes@google.com>
> CC: Jiang Liu <liuj97@gmail.com>
> CC: Len Brown <len.brown@intel.com>
> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> CC: Paul Mackerras <paulus@samba.org>
> CC: Christoph Lameter <cl@linux.com>
> Cc: Minchan Kim <minchan.kim@gmail.com>
> CC: Andrew Morton <akpm@linux-foundation.org>
> CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> CC: Wen Congyang <wency@cn.fujitsu.com>
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>
> ---
> drivers/base/node.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> Index: linux-3.5-rc6/drivers/base/node.c
> ===================================================================
> --- linux-3.5-rc6.orig/drivers/base/node.c 2012-07-18 18:24:29.191121066 +0900
> +++ linux-3.5-rc6/drivers/base/node.c 2012-07-18 18:25:47.111146983 +0900
> @@ -252,6 +252,12 @@ static inline void hugetlb_register_node
> static inline void hugetlb_unregister_node(struct node *node) {}
> #endif
>
> +static void node_device_release(struct device *dev)
> +{
> + struct node *node_dev = to_node(dev);
> +
> + memset(node_dev, 0, sizeof(struct node));

This line is wrong. node_dev->work_struct may be queued in workqueue.
So, it is very dangerous to clear node_dev->work_struct here.
In my test, it will cause kernel panicked.

Thanks
Wen Congyang
> +}
>
> /*
> * register_node - Setup a sysfs device for a node.
> @@ -265,6 +271,7 @@ int register_node(struct node *node, int
>
> node->dev.id = num;
> node->dev.bus = &node_subsys;
> + node->dev.release = node_device_release;
> error = device_register(&node->dev);
>
> if (!error){
>
> --
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