netdev - Re: [PATCH net] dpll: Prevent duplicate registrations

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Message-ID: <063f95d2-e29f-416d-8226-49a21b7c8dcd@linux.dev>
Date: Wed, 21 Jan 2026 17:18:58 +0000
From: Vadim Fedorenko <vadim.fedorenko@...ux.dev>
To: Ivan Vecera <ivecera@...hat.com>, netdev@...r.kernel.org
Cc: Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>,
 Jiri Pirko <jiri@...nulli.us>, "David S. Miller" <davem@...emloft.net>,
 Michal Michalik <michal.michalik@...el.com>,
 Milena Olech <milena.olech@...el.com>,
 open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net] dpll: Prevent duplicate registrations

On 21/01/2026 13:00, Ivan Vecera wrote:
> Modify the internal registration helpers dpll_xa_ref_{dpll,pin}_add()
> to reject duplicate registration attempts.
> 
> Previously, if a caller attempted to register the same pin multiple
> times (with the same ops, priv, and cookie) on the same device, the core
> silently increments the reference count and return success. This behavior
> is incorrect because if the caller makes these duplicate registrations
> then for the first one dpll_pin_registration is allocated and for others
> the associated dpll_pin_ref.refcount is incremented. During the first
> unregistration the associated dpll_pin_registration is freed and for
> others WARN is fired.
> 
> Fix this by updating the logic to return `-EEXIST` if a matching
> registration is found to enforce a strict "register once" policy.
> 
> Fixes: 9431063ad323 ("dpll: core: Add DPLL framework base functions")
> Signed-off-by: Ivan Vecera <ivecera@...hat.com>
> ---
>   drivers/dpll/dpll_core.c | 12 ++++--------
>   1 file changed, 4 insertions(+), 8 deletions(-)

Reviewed-by: Vadim Fedorenko <vadim.fedorenko@...ux.dev>