On Tue, 1 Apr 2014 13:51:26 +0800, Xiubo Li <[email protected]> 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 <[email protected]>
> ---
>  drivers/of/base.c | 24 +++++++++++-------------
>  1 file changed, 11 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 418a4ff9..34acb37 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)
> @@ -1776,25 +1776,26 @@ 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 node */
> +             rc = __of_add_property(np, newprop);
> +     } else {

if you changed this line to:
        } else while (*next) {
then most of the other changes go away. You don't need the separate
while loop and the function remains largely identical aside from moving
the __of_find_property() into the spinlock.

> +             next = &np->properties;
> +             while (*next && *next != oldprop)
> +                     next = &(*next)->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;
>       }
>       raw_spin_unlock_irqrestore(&devtree_lock, flags);
> +
>       if (rc)
>               return rc;
>  
> @@ -1803,9 +1804,6 @@ 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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