Re: [PATCH 3/3] thermal: intel: hfi: Enable interface only when required

[Jiri Pirko <jiri@resnulli.us>]

Wed, Jan 31, 2024 at 01:05:35PM CET, stanislaw.gruszka@linux.intel.com wrote:

[...]


>+static int hfi_netlink_notify(struct notifier_block *nb, unsigned long state,
>+			      void *_notify)
>+{
>+	struct netlink_notify *notify = _notify;
>+	struct hfi_instance *hfi_instance;
>+	smp_call_func_t func;
>+	unsigned int cpu;
>+	int i;
>+
>+	if (notify->protocol != NETLINK_GENERIC)
>+		return NOTIFY_DONE;
>+
>+	switch (state) {
>+	case NETLINK_CHANGE:
>+	case NETLINK_URELEASE:
>+		mutex_lock(&hfi_instance_lock);
>+

What's stopping other thread from mangling the listeners here?


>+		if (thermal_group_has_listeners(THERMAL_GENL_EVENT_GROUP))
>+			func = hfi_do_enable;
>+		else
>+			func = hfi_do_disable;
>+
>+		for (i = 0; i < max_hfi_instances; i++) {
>+			hfi_instance = &hfi_instances[i];
>+			if (cpumask_empty(hfi_instance->cpus))
>+				continue;
>+
>+			cpu = cpumask_any(hfi_instance->cpus);
>+			smp_call_function_single(cpu, func, hfi_instance, true);
>+		}
>+
>+		mutex_unlock(&hfi_instance_lock);
>+		return NOTIFY_OK;
>+	}
>+
>+	return NOTIFY_DONE;
>+}

[...]