On Thu, Apr 17, 2014 at 2:48 AM, Xiubo Li <Li.Xiubo@xxxxxxxxxxxxx> wrote:
> The of_update_property() is intented to update a property in a node
> and if the property does not exist, will add it.
>
> The second search of the property is possibly won't be found, that
> maybe removed by other thread just before the second search begain.
>
> Using the __of_find_property() and __of_add_property() instead and
> move them into lock operations.
I have a fix in my tree from Guenter which handles the race of the
property being removed. However, your change will be needed when we
have overlays and the node itself can be removed. So this is 3.16
material and will need to be rebased on Guenter's fix.
Rob
>
> Signed-off-by: Xiubo Li <Li.Xiubo@xxxxxxxxxxxxx>
> ---
> drivers/of/base.c | 18 +++++++-----------
> 1 file changed, 7 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index be2861d..06623d0c 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -1767,7 +1767,7 @@ int of_update_property(struct device_node *np, struct property *newprop)
> {
> struct property **next, *oldprop;
> unsigned long flags;
> - int rc, found = 0;
> + int rc;
>
> rc = of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop);
> if (rc)
> @@ -1776,20 +1776,19 @@ int of_update_property(struct device_node *np, struct property *newprop)
> if (!newprop->name)
> return -EINVAL;
>
> - oldprop = of_find_property(np, newprop->name, NULL);
> - if (!oldprop)
> - return of_add_property(np, newprop);
> -
> raw_spin_lock_irqsave(&devtree_lock, flags);
> next = &np->properties;
> - while (*next) {
> + oldprop = __of_find_property(np, newprop->name, NULL);
> + if (!oldprop) {
> + /* add the new node */
> + rc = __of_add_property(np, newprop);
> + } else while (*next) {
> + /* found the node and then replace it */
> if (*next == oldprop) {
> - /* found the node */
> newprop->next = oldprop->next;
> *next = newprop;
> oldprop->next = np->deadprops;
> np->deadprops = oldprop;
> - found = 1;
> break;
> }
> next = &(*next)->next;
> @@ -1803,9 +1802,6 @@ int of_update_property(struct device_node *np, struct property *newprop)
> sysfs_remove_bin_file(&np->kobj, &oldprop->attr);
> __of_add_property_sysfs(np, newprop);
>
> - if (!found)
> - return -ENODEV;
> -
> return 0;
> }
>
> --
> 1.8.4
>
>
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