netdev - [PATCH net v2 4/4] dpll: hide "zombie" pins for userspace

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Date: Thu,  4 Jan 2024 12:11:32 +0100
From: Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>
To: netdev@...r.kernel.org
Cc: vadim.fedorenko@...ux.dev,
	jiri@...nulli.us,
	michal.michalik@...el.com,
	milena.olech@...el.com,
	pabeni@...hat.com,
	kuba@...nel.org,
	Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>,
	Jan Glaza <jan.glaza@...el.com>
Subject: [PATCH net v2 4/4] dpll: hide "zombie" pins for userspace

If parent pin was unregistered but child pin was not, the userspace
would see the "zombie" pins - the ones that were registered with
parent pin (pins_pin_on_pin_register(..)).
Technically those are not available - as there is no dpll device in the
system. Do not dump those pins and prevent userspace from any
interaction with them.

Fixes: 9431063ad323 ("dpll: core: Add DPLL framework base functions")
Fixes: 9d71b54b65b1 ("dpll: netlink: Add DPLL framework base functions")
Reviewed-by: Jan Glaza <jan.glaza@...el.com>
Signed-off-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>
---
 drivers/dpll/dpll_netlink.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c
index f266db8da2f0..495dfc43c0be 100644
--- a/drivers/dpll/dpll_netlink.c
+++ b/drivers/dpll/dpll_netlink.c
@@ -949,6 +949,19 @@ dpll_pin_parent_pin_set(struct dpll_pin *pin, struct nlattr *parent_nest,
 	return 0;
 }
 
+static bool dpll_pin_parents_registered(struct dpll_pin *pin)
+{
+	struct dpll_pin_ref *par_ref;
+	struct dpll_pin *p;
+	unsigned long i, j;
+
+	xa_for_each(&pin->parent_refs, i, par_ref)
+		xa_for_each_marked(&dpll_pin_xa, j, p, DPLL_REGISTERED)
+			if (par_ref->pin == p)
+				return true;
+	return false;
+}
+
 static int
 dpll_pin_set_from_nlattr(struct dpll_pin *pin, struct genl_info *info)
 {
@@ -1153,6 +1166,9 @@ int dpll_nl_pin_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 
 	xa_for_each_marked_start(&dpll_pin_xa, i, pin, DPLL_REGISTERED,
 				 ctx->idx) {
+		if (!xa_empty(&pin->parent_refs) &&
+		    !dpll_pin_parents_registered(pin))
+			continue;
 		hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid,
 				  cb->nlh->nlmsg_seq,
 				  &dpll_nl_family, NLM_F_MULTI,
@@ -1179,6 +1195,10 @@ int dpll_nl_pin_set_doit(struct sk_buff *skb, struct genl_info *info)
 {
 	struct dpll_pin *pin = info->user_ptr[0];
 
+	if (!xa_empty(&pin->parent_refs) &&
+	    !dpll_pin_parents_registered(pin))
+		return -ENODEV;
+
 	return dpll_pin_set_from_nlattr(pin, info);
 }
 
-- 
2.38.1