RE: [PATCH v14 net-next 03/13] dpll: fix stale iteration in dpll_pin_on_pin_unregister()

[Kubalewski, Arkadiusz]

>From: Nitka, Grzegorz <grzegorz.nitka@xxxxxxxxx>
>Sent: Sunday, June 7, 2026 8:31 PM
>
>Neither parent->dpll_refs nor pin->dpll_refs on its own is a correct
>iteration target at unregister time:
>
>  - pin->dpll_refs includes DPLLs the child was registered against
>    via a different parent or directly; blind unregister WARNs on
>    the cookie miss in dpll_xa_ref_pin_del().
>  - parent->dpll_refs reflects the parent's current attachments, not
>    those at child-register time. Another driver may have (un)reg'd
>    the parent against additional DPLLs in the meantime, so we miss
>    registrations that exist and visit DPLLs that have none.
>
>Walk pin->dpll_refs and use dpll_pin_registration_find() to filter
>to entries whose cookie is this parent. Symmetric with
>dpll_pin_on_pin_register(), correct under any subsequent change to
>parent->dpll_refs.
>
>Fixes: 9431063ad323 ("dpll: core: Add DPLL framework base functions")
>Signed-off-by: Grzegorz Nitka <grzegorz.nitka@xxxxxxxxx>
>---
> drivers/dpll/dpll_core.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/dpll/dpll_core.c b/drivers/dpll/dpll_core.c
>index 6dc7e93ece75..cea7e2be2cbc 100644
>--- a/drivers/dpll/dpll_core.c
>+++ b/drivers/dpll/dpll_core.c
>@@ -1031,14 +1031,19 @@ EXPORT_SYMBOL_GPL(dpll_pin_on_pin_register);
> void dpll_pin_on_pin_unregister(struct dpll_pin *parent, struct dpll_pin
>*pin,
> 				const struct dpll_pin_ops *ops, void *priv)
> {
>+	struct dpll_pin_registration *reg;
> 	struct dpll_pin_ref *ref;
> 	unsigned long i;
>
> 	mutex_lock(&dpll_lock);
> 	dpll_pin_delete_ntf(pin);

Hey Grzegorz,

This line is redundant after 7/13?

> 	dpll_xa_ref_pin_del(&pin->parent_refs, parent, ops, priv, pin);
>-	xa_for_each(&pin->dpll_refs, i, ref)
>+	xa_for_each(&pin->dpll_refs, i, ref) {
>+		reg = dpll_pin_registration_find(ref, ops, priv, parent);
>+		if (!reg)
>+			continue;
> 		__dpll_pin_unregister(ref->dpll, pin, ops, priv, parent);
>+	}
> 	mutex_unlock(&dpll_lock);
> }
> EXPORT_SYMBOL_GPL(dpll_pin_on_pin_unregister);
>--
>2.39.3