[PATCH net 1/2] dpll: notify about a reference sync pair only if it was added

[Ivan Vecera <ivecera@redhat.com>]

dpll_pin_ref_sync_pair_add() sends a pin change notification even when
xa_insert() fails and nothing has changed. zl3073x gets -EBUSY when
another channel has already added the same pair and ignores it, so user
space is notified about a change that did not happen.

Send the notification only after a successful insert.

Found by code review. Reproduced on a ZL30732A board with kprobes on
dpll_pin_ref_sync_pair_add() and __dpll_pin_change_ntf(): loading the
driver adds one pair twice and the add failing with -EBUSY sends a
notification. With this patch it does not, and the successful add still
does. A test module adding one pair twice shows the same on the monitor
group.

Fixes: 58256a26bfb3 ("dpll: add reference sync get/set")
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
---
 drivers/dpll/dpll_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/dpll/dpll_core.c b/drivers/dpll/dpll_core.c
index 8389983f425695..277692d12d3d1e 100644
--- a/drivers/dpll/dpll_core.c
+++ b/drivers/dpll/dpll_core.c
@@ -1081,7 +1081,8 @@ int dpll_pin_ref_sync_pair_add(struct dpll_pin *pin,
 	mutex_lock(&dpll_lock);
 	ret = xa_insert(&pin->ref_sync_pins, ref_sync_pin->id,
 			ref_sync_pin, GFP_KERNEL);
-	__dpll_pin_change_ntf(pin);
+	if (!ret)
+		__dpll_pin_change_ntf(pin);
 	mutex_unlock(&dpll_lock);
 
 	return ret;
-- 
2.56.0