linux-kernel - Re: [PATCH net] devlink: rate: Unset parent pointer in devl_rate_nodes

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Message-ID: <20251112181248.190415f7@kernel.org>
Date: Wed, 12 Nov 2025 18:12:48 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: Tariq Toukan <tariqt@...dia.com>
Cc: Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
 Andrew Lunn <andrew+netdev@...n.ch>, "David S. Miller"
 <davem@...emloft.net>, Jiri Pirko <jiri@...nulli.us>,
 <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Mark Bloch
 <mbloch@...dia.com>, Gal Pressman <gal@...dia.com>, Leon Romanovsky
 <leonro@...dia.com>, Cosmin Ratiu <cratiu@...dia.com>, Moshe Shemesh
 <moshe@...dia.com>, Jiri Pirko <jiri@...dia.com>, Carolina Jubran
 <cjubran@...dia.com>, Shay Drory <shayd@...dia.com>
Subject: Re: [PATCH net] devlink: rate: Unset parent pointer in
 devl_rate_nodes_destroy

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