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

[Tariq Toukan <tariqt@nvidia.com>]

From: Shay Drory <shayd@nvidia.com>

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.

Fixes: d75559845078 ("devlink: Allow setting parent node of rate objects")
Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Carolina Jubran <cjubran@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 net/devlink/rate.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/devlink/rate.c b/net/devlink/rate.c
index 264fb82cba19..d157a8419bca 100644
--- a/net/devlink/rate.c
+++ b/net/devlink/rate.c
@@ -828,13 +828,15 @@ void devl_rate_nodes_destroy(struct devlink *devlink)
 		if (!devlink_rate->parent)
 			continue;
 
-		refcount_dec(&devlink_rate->parent->refcnt);
 		if (devlink_rate_is_leaf(devlink_rate))
 			ops->rate_leaf_parent_set(devlink_rate, NULL, devlink_rate->priv,
 						  NULL, NULL);
 		else if (devlink_rate_is_node(devlink_rate))
 			ops->rate_node_parent_set(devlink_rate, NULL, devlink_rate->priv,
 						  NULL, NULL);
+
+		refcount_dec(&devlink_rate->parent->refcnt);
+		devlink_rate->parent = NULL;
 	}
 	list_for_each_entry_safe(devlink_rate, tmp, &devlink->rate_list, list) {
 		if (devlink_rate_is_node(devlink_rate)) {

base-commit: 8c0726e861f3920bac958d76cf134b5a3aa14ce4
-- 
2.31.1