dpll: Add reference count tracking support

Add support for the REF_TRACKER infrastructure to the DPLL subsystem.

When enabled, this allows developers to track and debug reference counting
leaks or imbalances for dpll_device and dpll_pin objects. It records stack
traces for every get/put operation and exposes this information via
debugfs at:
  /sys/kernel/debug/ref_tracker/dpll_device_*
  /sys/kernel/debug/ref_tracker/dpll_pin_*

The following API changes are made to support this:
1. dpll_device_get() / dpll_device_put() now accept a 'dpll_tracker *'
   (which is a typedef to 'struct ref_tracker *' when enabled, or an empty
   struct otherwise).
2. dpll_pin_get() / dpll_pin_put() and fwnode_dpll_pin_find() similarly
   accept the tracker argument.
3. Internal registration structures now hold a tracker to associate the
   reference held by the registration with the specific owner.

All existing in-tree drivers (ice, mlx5, ptp_ocp, zl3073x) are updated
to pass NULL for the new tracker argument, maintaining current behavior
while enabling future debugging capabilities.

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Co-developed-by: Petr Oros <poros@redhat.com>
Signed-off-by: Petr Oros <poros@redhat.com>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Reviewed-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@intel.com>
Link: https://patch.msgid.link/20260203174002.705176-8-ivecera@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 15 insertions, 6 deletions

diff --git a/include/linux/dpll.h b/include/linux/dpll.h
index 8fff048131f1..2ce295b46b8c 100644
--- a/include/linux/dpll.h
+++ b/include/linux/dpll.h
@@ -18,6 +18,7 @@ struct dpll_device;
 struct dpll_pin;
 struct dpll_pin_esync;
 struct fwnode_handle;
+struct ref_tracker;
 
 struct dpll_device_ops {
 	int (*mode_get)(const struct dpll_device *dpll, void *dpll_priv,
@@ -173,6 +174,12 @@ struct dpll_pin_properties {
 	u32 phase_gran;
 };
 
+#ifdef CONFIG_DPLL_REFCNT_TRACKER
+typedef struct ref_tracker *dpll_tracker;
+#else
+typedef struct {} dpll_tracker;
+#endif
+
 #define DPLL_DEVICE_CREATED	1
 #define DPLL_DEVICE_DELETED	2
 #define DPLL_DEVICE_CHANGED	3
@@ -205,7 +212,8 @@ size_t dpll_netdev_pin_handle_size(const struct net_device *dev);
 int dpll_netdev_add_pin_handle(struct sk_buff *msg,
 			       const struct net_device *dev);
 
-struct dpll_pin *fwnode_dpll_pin_find(struct fwnode_handle *fwnode);
+struct dpll_pin *fwnode_dpll_pin_find(struct fwnode_handle *fwnode,
+				      dpll_tracker *tracker);
 #else
 static inline void
 dpll_netdev_pin_set(struct net_device *dev, struct dpll_pin *dpll_pin) { }
@@ -223,16 +231,17 @@ dpll_netdev_add_pin_handle(struct sk_buff *msg, const struct net_device *dev)
 }
 
 static inline struct dpll_pin *
-fwnode_dpll_pin_find(struct fwnode_handle *fwnode)
+fwnode_dpll_pin_find(struct fwnode_handle *fwnode, dpll_tracker *tracker)
 {
 	return NULL;
 }
 #endif
 
 struct dpll_device *
-dpll_device_get(u64 clock_id, u32 dev_driver_id, struct module *module);
+dpll_device_get(u64 clock_id, u32 dev_driver_id, struct module *module,
+		dpll_tracker *tracker);
 
-void dpll_device_put(struct dpll_device *dpll);
+void dpll_device_put(struct dpll_device *dpll, dpll_tracker *tracker);
 
 int dpll_device_register(struct dpll_device *dpll, enum dpll_type type,
 			 const struct dpll_device_ops *ops, void *priv);
@@ -244,7 +253,7 @@ void dpll_device_unregister(struct dpll_device *dpll,
 
 struct dpll_pin *
 dpll_pin_get(u64 clock_id, u32 dev_driver_id, struct module *module,
-	     const struct dpll_pin_properties *prop);
+	     const struct dpll_pin_properties *prop, dpll_tracker *tracker);
 
 int dpll_pin_register(struct dpll_device *dpll, struct dpll_pin *pin,
 		      const struct dpll_pin_ops *ops, void *priv);
@@ -252,7 +261,7 @@ int dpll_pin_register(struct dpll_device *dpll, struct dpll_pin *pin,
 void dpll_pin_unregister(struct dpll_device *dpll, struct dpll_pin *pin,
 			 const struct dpll_pin_ops *ops, void *priv);
 
-void dpll_pin_put(struct dpll_pin *pin);
+void dpll_pin_put(struct dpll_pin *pin, dpll_tracker *tracker);
 
 void dpll_pin_fwnode_set(struct dpll_pin *pin, struct fwnode_handle *fwnode);