Re: [PATCH net] devlink: rate: Unset parent pointer in devl_rate_nodes_destroy

[Shay Drori]

On 13/11/2025 4:12, Jakub Kicinski wrote:
> External email: Use caution opening links or attachments
>
>
> On Tue, 11 Nov 2025 14:14:39 +0200 Tariq Toukan wrote:
> > The function devl_rate_nodes_destroy is documented to "Unset parent for
> > all rate objects". However, it was only calling the driver-specific
> > `rate_leaf_parent_set` or `rate_node_parent_set` ops and decrementing
> > the parent's refcount, without actually setting the
> > `devlink_rate->parent` pointer to NULL.
> >
> > This leaves a dangling pointer in the `devlink_rate` struct, which is
> > inconsistent with the behavior of `devlink_nl_rate_parent_node_set`,
> > where the parent pointer is correctly cleared.
> >
> > This patch fixes the issue by explicitly setting `devlink_rate->parent`
> > to NULL after notifying the driver, thus fulfilling the function's
> > documented behavior for all rate objects.
>
> What is the _real_ issue you're solving here? If the function destroys
> all nodes maybe it doesn't matter that the pointer isn't cleared.
> --
> pw-bot: cr

The problem is a leaf which have this node as a parent, now pointing to
invalid memory. When this leaf will be destroyed, in
devl_rate_leaf_destroy, we can get NULL-ptr error, or refcount error.

Is this answer your question?