Subject: Re: [PATCH net 3/3] dpll: fix register pin with unregistered parent pin

From: Jiri Pirko <[email-masked]>
Date: Wed, 8 Nov 2023 16:07:41 +0100

Wed, Nov 08, 2023 at 11:32:26AM CET, [email-masked] wrote:
>In case of multiple kernel module instances using the same dpll device:
>if only one registers dpll device, then only that one can register

They why you don't register in multiple instances? See mlx5 for a
reference.

>directly connected pins with a dpll device. If unregistered parent
>determines if the muxed pin can be register with it or not, it forces
>serialized driver load order - first the driver instance which registers
>the direct pins needs to be loaded, then the other instances could
>register muxed type pins.
>
>Allow registration of a pin with a parent even if the parent was not
>yet registered, thus allow ability for unserialized driver instance

Weird.

>load order.
>Do not WARN_ON notification for unregistered pin, which can be invoked
>for described case, instead just return error.
>
>Fixes: 9431063ad323 ("dpll: core: Add DPLL framework base functions")
>Fixes: 9d71b54b65b1 ("dpll: netlink: Add DPLL framework base functions")
>Signed-off-by: Arkadiusz Kubalewski <[email-masked]>
>---
> drivers/dpll/dpll_core.c    | 4 ----
> drivers/dpll/dpll_netlink.c | 2 +-
> 2 files changed, 1 insertion(+), 5 deletions(-)
>
>diff --git a/drivers/dpll/dpll_core.c b/drivers/dpll/dpll_core.c
>index 4077b562ba3b..ae884b92d68c 100644
>--- a/drivers/dpll/dpll_core.c
>+++ b/drivers/dpll/dpll_core.c
>@@ -28,8 +28,6 @@ static u32 dpll_xa_id;
> 	WARN_ON_ONCE(!xa_get_mark(&dpll_device_xa, (d)->id, DPLL_REGISTERED))
> #define ASSERT_DPLL_NOT_REGISTERED(d)	\
> 	WARN_ON_ONCE(xa_get_mark(&dpll_device_xa, (d)->id, DPLL_REGISTERED))
>-#define ASSERT_PIN_REGISTERED(p)	\
>-	WARN_ON_ONCE(!xa_get_mark(&dpll_pin_xa, (p)->id, DPLL_REGISTERED))
> 
> struct dpll_device_registration {
> 	struct list_head list;
>@@ -641,8 +639,6 @@ int dpll_pin_on_pin_register(struct dpll_pin *parent, struct dpll_pin *pin,
> 	    WARN_ON(!ops->state_on_pin_get) ||
> 	    WARN_ON(!ops->direction_get))
> 		return -EINVAL;
>-	if (ASSERT_PIN_REGISTERED(parent))
>-		return -EINVAL;
> 
> 	mutex_lock(&dpll_lock);
> 	ret = dpll_xa_ref_pin_add(&pin->parent_refs, parent, ops, priv);
>diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c
>index 963bbbbe6660..ff430f43304f 100644
>--- a/drivers/dpll/dpll_netlink.c
>+++ b/drivers/dpll/dpll_netlink.c
>@@ -558,7 +558,7 @@ dpll_pin_event_send(enum dpll_cmd event, struct dpll_pin *pin)
> 	int ret = -ENOMEM;
> 	void *hdr;
> 
>-	if (WARN_ON(!xa_get_mark(&dpll_pin_xa, pin->id, DPLL_REGISTERED)))
>+	if (!xa_get_mark(&dpll_pin_xa, pin->id, DPLL_REGISTERED))
> 		return -ENODEV;
> 
> 	msg = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
>-- 
>2.38.1
>