Re: [PATCH net-next 04/10] dpll: take domain locks around driver callbacks

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found no new issues
in this patch, but noticed 1 related pre-existing issue it does not
introduce:
- [Medium] dpll: broken NLM_F_ECHO in dpll_pin_event_send() [1]
--

commit 1d6bef1472d6edb1fb63ca2b725c77cbbc70a8da
Author: Ivan Vecera <ivecera@redhat.com>

dpll: take domain locks around driver callbacks

This commit acquires the object's domain lock around driver callbacks in
netlink requests, dumps, and notifications.

> diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c
> index e5380d95f238b..1b4e3a0166a74 100644
> --- a/drivers/dpll/dpll_netlink.c
> +++ b/drivers/dpll/dpll_netlink.c

[ ... ]

> @@ -941,27 +955,39 @@ dpll_pin_event_send(enum dpll_cmd event, struct dpll_pin *pin)
>  
>  int dpll_pin_create_ntf(struct dpll_pin *pin, u64 src_clock_id)
>  {
> +	int ret;
> +
> +	mutex_lock(&pin->domain->lock);
>  	dpll_pin_notify(pin, src_clock_id, DPLL_PIN_CREATED);
> -	return dpll_pin_event_send(DPLL_CMD_PIN_CREATE_NTF, pin);
> +	ret = dpll_pin_event_send(DPLL_CMD_PIN_CREATE_NTF, pin);
> +	mutex_unlock(&pin->domain->lock);
> +
> +	return ret;
>  }

[Severity: Medium]
This problem wasn't introduced by this patch, but does dpll_pin_event_send()
break NLM_F_ECHO on pin SET requests [1]?

drivers/dpll/dpll_netlink.c:dpll_pin_event_send() {
	...
	hdr = genlmsg_put(msg, 0, 0, &dpll_nl_family, 0, event);
	...
	genlmsg_end(msg, hdr);
	genlmsg_multicast(&dpll_nl_family, msg, 0, 0, GFP_KERNEL);
	...
}

When a user-space SET request triggers a pin change notification,
dpll_pin_event_send() is called without the request's genl_info context.
Passing a portid of 0 to genlmsg_put() and calling genlmsg_multicast()
instead of genl_notify() drops the originating socket information, so user
space never receives the requested NLM_F_ECHO notification.

[1] https://sashiko.dev/#/bug/linux-14884b2c-eeea-47fd-87fe-40bc535d32cc

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261106121005.1327603-1-ivecera@redhat.com?part=4