Re: [PATCH net 1/2] dpll: notify about a reference sync pair only if it was added

[Vadim Fedorenko <vadim.fedorenko@linux.dev>]

On 05/11/2026 13:11, Ivan Vecera wrote:
> dpll_pin_ref_sync_pair_add() sends a pin change notification even when
> xa_insert() fails and nothing has changed. zl3073x gets -EBUSY when
> another channel has already added the same pair and ignores it, so user
> space is notified about a change that did not happen.
> 
> Send the notification only after a successful insert.
> 
> Found by code review. Reproduced on a ZL30732A board with kprobes on
> dpll_pin_ref_sync_pair_add() and __dpll_pin_change_ntf(): loading the
> driver adds one pair twice and the add failing with -EBUSY sends a
> notification. With this patch it does not, and the successful add still
> does. A test module adding one pair twice shows the same on the monitor
> group.
> 
> Fixes: 58256a26bfb3 ("dpll: add reference sync get/set")
> Signed-off-by: Ivan Vecera <ivecera@redhat.com>
> ---
>   drivers/dpll/dpll_core.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/dpll/dpll_core.c b/drivers/dpll/dpll_core.c
> index 8389983f425695..277692d12d3d1e 100644
> --- a/drivers/dpll/dpll_core.c
> +++ b/drivers/dpll/dpll_core.c
> @@ -1081,7 +1081,8 @@ int dpll_pin_ref_sync_pair_add(struct dpll_pin *pin,
>   	mutex_lock(&dpll_lock);
>   	ret = xa_insert(&pin->ref_sync_pins, ref_sync_pin->id,
>   			ref_sync_pin, GFP_KERNEL);
> -	__dpll_pin_change_ntf(pin);
> +	if (!ret)
> +		__dpll_pin_change_ntf(pin);
>   	mutex_unlock(&dpll_lock);
>   
>   	return ret;

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