On Wed, 22 Jan 2014 13:57:40 +0800, 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.
>
> Signed-off-by: Xiubo Li <Li.Xiubo@xxxxxxxxxxxxx>
> Cc: Pantelis Antoniou <panto@xxxxxxxxxxxxxxxxxxxxxxx>
I've had to revert this patch. See below...
> ---
> drivers/of/base.c | 36 ++++++++++++++----------------------
> 1 file changed, 14 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index b86b77a..458072d 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -1573,7 +1573,7 @@ int of_update_property(struct device_node *np, struct property *newprop)
> {
> struct property **next, *oldprop;
> unsigned long flags;
> - int rc, found = 0;
> + int rc = 0;
>
> rc = of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop);
> if (rc)
> @@ -1582,36 +1582,28 @@ 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) {
> - 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;
> + oldprop = __of_find_property(np, newprop->name, NULL);
> + if (!oldprop) {
> + /* add the node */
> + rc = __of_add_property(np, newprop);
> + } else {
> + /* replace the node */
> + next = &oldprop;
Ugh. I just looked closer and the above line is completely broken.
&oldprop is the address of 'oldprop' on the stack, *not* the address of
the previous item in the list. The while loop is still required to find it.
g.
> + newprop->next = oldprop->next;
> + *next = newprop;
> + oldprop->next = np->deadprops;
> + np->deadprops = oldprop;
> }
> raw_spin_unlock_irqrestore(&devtree_lock, flags);
>
> - if (!found)
> - return -ENODEV;
> -
> #ifdef CONFIG_PROC_DEVICETREE
> /* try to add to proc as well if it was initialized */
> - if (np->pde)
> + if (!rc && np->pde)
> proc_device_tree_update_prop(np->pde, newprop, oldprop);
> #endif /* CONFIG_PROC_DEVICETREE */
>
> - return 0;
> + return rc;
> }
>
> #if defined(CONFIG_OF_DYNAMIC)
> --
> 1.8.4
>
>
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