[PATCH 1/2] clk: Do not register provider with a NULL dev->of_node

Tudor Ambarus
2021-04-23T17:14:01Z

commit 6579c8d97ad7 ("clk: Mark fwnodes when their clock provider is added")
revealed that clk/bcm/clk-raspberrypi.c driver calls
devm_of_clk_add_hw_provider(), with a NULL dev->of_node.

devm_of_clk_add_hw_provider() should not register the provider with
a NULL dev->of_node, as there is no of_node. Apart of the NULL pointer
dereference that will result when calling fwnode_dev_initialized() in
of_clk_add_hw_provider(), another problem is that when two drivers calling
of_clk_add_hw_provider() with np = NULL, their unregistration order is not
guaranteed to be correct. Avoid all the problems and just return -ENODEV
when the callers of devm_of_clk_add_hw_provider() use a NULL dev->of_node,
which seems the natural way to do.

Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Fixes: 6579c8d97ad7 ("clk: Mark fwnodes when their clock provider is added")
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---
drivers/clk/clk.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index e2ec1b745243..8b5077cc5e67 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -4634,11 +4634,10 @@ static struct device_node *get_clk_provider_node(struct device *dev)
* @get: callback for decoding clk_hw
* @data: context pointer for @get callback
*
- * Registers clock provider for given device's node. If the device has no DT
- * node or if the device node lacks of clock provider information (#clock-cells)
- * then the parent device's node is scanned for this information. If parent node
- * has the #clock-cells then it is used in registration. Provider is
- * automatically released at device exit.
+ * Registers clock provider for given device's node. If the device node lacks
+ * of clock provider information (#clock-cells) then the parent device's node is
+ * scanned for this information. If parent node has the #clock-cells then it is
+ * used in registration. Provider is automatically released at device exit.
*
* Return: 0 on success or an errno on failure.
*/
@@ -4650,6 +4649,9 @@ int devm_of_clk_add_hw_provider(struct device *dev,
struct device_node **ptr, *np;
int ret;

+ if (!dev->of_node)
+ return -ENODEV;
+
ptr = devres_alloc(devm_of_clk_release_provider, sizeof(*ptr),
GFP_KERNEL);
if (!ptr)
--
2.25.1