[PATCH net-next 04/10] dpll: take domain locks around driver callbacks

@@ -520,7 +520,7 @@ dpll_device_registration_find(struct dpll_device *dpll,
  *
  * Make dpll device available for user space.
  *
- * Context: Acquires a lock (dpll_lock)
+ * Context: Acquires dpll_lock and the domain lock of @dpll
  * Return:
  * * 0 on success
  * * negative - error value

@@ -579,7 +579,7 @@ EXPORT_SYMBOL_GPL(dpll_device_register);
  *
  * Unregister device, make it unavailable for userspace.
  * Note: It does not free the memory
- * Context: Acquires a lock (dpll_lock)
+ * Context: Acquires dpll_lock and the domain lock of @dpll
  */
 void dpll_device_unregister(struct dpll_device *dpll,
 			    const struct dpll_device_ops *ops, void *priv)

@@ -928,7 +928,7 @@ __dpll_pin_register(struct dpll_device *dpll, struct dpll_pin *pin,
  * @ops: ops for a dpll pin ops
  * @priv: pointer to private information of owner
  *
- * Context: Acquires a lock (dpll_lock)
+ * Context: Acquires dpll_lock and domain locks
  * Return:
  * * 0 on success
  * * negative - error value

@@ -989,7 +989,9 @@ static void dpll_pin_ref_sync_pair_del(u32 ref_sync_pin_id)
 		ref_sync_pin = xa_load(&pin->ref_sync_pins, ref_sync_pin_id);
 		if (ref_sync_pin) {
 			xa_erase(&pin->ref_sync_pins, ref_sync_pin_id);
+			mutex_lock(&pin->domain->lock);
 			__dpll_pin_change_ntf(pin);
+			mutex_unlock(&pin->domain->lock);
 		}
 	}
 }

@@ -1016,7 +1018,7 @@ __dpll_pin_unregister(struct dpll_device *dpll, struct dpll_pin *pin,
  * @priv: pointer to private information of owner
  *
  * Note: It does not free the memory
- * Context: Acquires a lock (dpll_lock)
+ * Context: Acquires dpll_lock and domain locks
  */
 void dpll_pin_unregister(struct dpll_device *dpll, struct dpll_pin *pin,
 			 const struct dpll_pin_ops *ops, void *priv)

@@ -1042,7 +1044,7 @@ EXPORT_SYMBOL_GPL(dpll_pin_unregister);
  * Register a pin with a parent pin, create references between them and
  * between newly registered pin and dplls connected with a parent pin.
  *
- * Context: Acquires a lock (dpll_lock)
+ * Context: Acquires dpll_lock and domain locks
  * Return:
  * * 0 on success
  * * negative - error value

@@ -1099,7 +1101,7 @@ EXPORT_SYMBOL_GPL(dpll_pin_on_pin_register);
  * @ops: ops for a dpll pin
  * @priv: pointer to private information of owner
  *
- * Context: Acquires a lock (dpll_lock)
+ * Context: Acquires dpll_lock and domain locks
  * Note: It does not free the memory
  */
 void dpll_pin_on_pin_unregister(struct dpll_pin *parent, struct dpll_pin *pin,

@@ -1129,7 +1131,7 @@ EXPORT_SYMBOL_GPL(dpll_pin_on_pin_unregister);
  *
  * Once pins are paired, the user-space configuration of reference sync pair
  * is possible.
- * Context: Acquires a lock (dpll_lock)
+ * Context: Acquires dpll_lock and domain locks
  * Return:
  * * 0 on success
  * * negative - error value

@@ -1142,7 +1144,9 @@ 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);
+	mutex_lock(&pin->domain->lock);
 	__dpll_pin_change_ntf(pin);
+	mutex_unlock(&pin->domain->lock);
 	mutex_unlock(&dpll_lock);
 
 	return ret;

@@ -22,10 +22,14 @@
  * @clock_id:		clock_id of the objects in the domain
  * @module:		module of the objects in the domain
  * @refcount:		number of dpll devices and pins in the domain
- * @lock:		lock of the domain
+ * @lock:		serializes driver callbacks of the domain
  *
  * All dpll devices and pins created with the same (module, clock_id) pair
  * belong to one domain, in practice to one chip or card.
+ *
+ * Callbacks of a device run under the domain of the device and callbacks of a
+ * pin under the domain of the pin, whichever driver registered them. Only one
+ * domain lock is held at a time, so domains have no lock order.
  **/
 struct dpll_domain {
 	u32 id;

@@ -861,27 +861,39 @@ dpll_device_event_send(enum dpll_cmd event, struct dpll_device *dpll)
 
 int dpll_device_create_ntf(struct dpll_device *dpll)
 {
+	int ret;
+
+	mutex_lock(&dpll->domain->lock);
 	dpll_device_notify(dpll, DPLL_DEVICE_CREATED);
-	return dpll_device_event_send(DPLL_CMD_DEVICE_CREATE_NTF, dpll);
+	ret = dpll_device_event_send(DPLL_CMD_DEVICE_CREATE_NTF, dpll);
+	mutex_unlock(&dpll->domain->lock);
+
+	return ret;
 }
 
 int dpll_device_delete_ntf(struct dpll_device *dpll)
 {
+	int ret;
+
+	mutex_lock(&dpll->domain->lock);
 	dpll_device_notify(dpll, DPLL_DEVICE_DELETED);
-	return dpll_device_event_send(DPLL_CMD_DEVICE_DELETE_NTF, dpll);
+	ret = dpll_device_event_send(DPLL_CMD_DEVICE_DELETE_NTF, dpll);
+	mutex_unlock(&dpll->domain->lock);
+
+	return ret;
 }
 
 /**
  * __dpll_device_change_ntf - notify that the dpll device has been changed
  * @dpll: registered dpll pointer
  *
- * Context: caller must hold dpll_lock. Suitable for use inside device
- *          callbacks which are already invoked under dpll_lock.
+ * Context: caller must hold dpll_lock and the domain lock of @dpll.
+ *          Suitable for use inside callbacks running under these locks.
  * Return: 0 if succeeds, error code otherwise.
  */
 int __dpll_device_change_ntf(struct dpll_device *dpll)
 {
-	lockdep_assert_held(&dpll_lock);
+	lockdep_assert_held(&dpll->domain->lock);
 	dpll_device_notify(dpll, DPLL_DEVICE_CHANGED);
 	return dpll_device_event_send(DPLL_CMD_DEVICE_CHANGE_NTF, dpll);
 }

@@ -891,7 +903,7 @@ EXPORT_SYMBOL_GPL(__dpll_device_change_ntf);
  * dpll_device_change_ntf - notify that the dpll device has been changed
  * @dpll: registered dpll pointer
  *
- * Context: acquires and holds a dpll_lock.
+ * Context: acquires and holds dpll_lock and the domain lock of @dpll.
  * Return: 0 if succeeds, error code otherwise.
  */
 int dpll_device_change_ntf(struct dpll_device *dpll)

@@ -899,7 +911,9 @@ int dpll_device_change_ntf(struct dpll_device *dpll)
 	int ret;
 
 	mutex_lock(&dpll_lock);
+	mutex_lock(&dpll->domain->lock);
 	ret = __dpll_device_change_ntf(dpll);
+	mutex_unlock(&dpll->domain->lock);
 	mutex_unlock(&dpll_lock);
 
 	return ret;

@@ -941,27 +955,39 @@ dpll_pin_event_send(enum dpll_cmd event, struct dpll_pin *pin)
 
 int dpll_pin_create_ntf(struct dpll_pin *pin, u64 src_clock_id)
 {
+	int ret;
+
+	mutex_lock(&pin->domain->lock);
 	dpll_pin_notify(pin, src_clock_id, DPLL_PIN_CREATED);
-	return dpll_pin_event_send(DPLL_CMD_PIN_CREATE_NTF, pin);
+	ret = dpll_pin_event_send(DPLL_CMD_PIN_CREATE_NTF, pin);
+	mutex_unlock(&pin->domain->lock);
+
+	return ret;
 }
 
 int dpll_pin_delete_ntf(struct dpll_pin *pin, u64 src_clock_id)
 {
+	int ret;
+
+	mutex_lock(&pin->domain->lock);
 	dpll_pin_notify(pin, src_clock_id, DPLL_PIN_DELETED);
-	return dpll_pin_event_send(DPLL_CMD_PIN_DELETE_NTF, pin);
+	ret = dpll_pin_event_send(DPLL_CMD_PIN_DELETE_NTF, pin);
+	mutex_unlock(&pin->domain->lock);
+
+	return ret;
 }
 
 /**
  * __dpll_pin_change_ntf - notify that the pin has been changed
  * @pin: registered pin pointer
  *
- * Context: caller must hold dpll_lock. Suitable for use inside pin
- *          callbacks which are already invoked under dpll_lock.
+ * Context: caller must hold dpll_lock and the domain lock of @pin.
+ *          Suitable for use inside callbacks running under these locks.
  * Return: 0 if succeeds, error code otherwise.
  */
 int __dpll_pin_change_ntf(struct dpll_pin *pin)
 {
-	lockdep_assert_held(&dpll_lock);
+	lockdep_assert_held(&pin->domain->lock);
 	dpll_pin_notify(pin, pin->clock_id, DPLL_PIN_CHANGED);
 	return dpll_pin_event_send(DPLL_CMD_PIN_CHANGE_NTF, pin);
 }

@@ -971,7 +997,7 @@ EXPORT_SYMBOL_GPL(__dpll_pin_change_ntf);
  * dpll_pin_change_ntf - notify that the pin has been changed
  * @pin: registered pin pointer
  *
- * Context: acquires and holds a dpll_lock.
+ * Context: acquires and holds dpll_lock and the domain lock of @pin.
  * Return: 0 if succeeds, error code otherwise.
  */
 int dpll_pin_change_ntf(struct dpll_pin *pin)

@@ -979,7 +1005,9 @@ int dpll_pin_change_ntf(struct dpll_pin *pin)
 	int ret;
 
 	mutex_lock(&dpll_lock);
+	mutex_lock(&pin->domain->lock);
 	ret = __dpll_pin_change_ntf(pin);
+	mutex_unlock(&pin->domain->lock);
 	mutex_unlock(&dpll_lock);
 
 	return ret;

@@ -1780,7 +1808,9 @@ int dpll_nl_pin_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 			ret = -EMSGSIZE;
 			break;
 		}
+		mutex_lock(&pin->domain->lock);
 		ret = dpll_cmd_pin_get_one(skb, pin, cb->extack);
+		mutex_unlock(&pin->domain->lock);
 		if (ret) {
 			genlmsg_cancel(skb, hdr);
 			if (ret == -ENODEV) {

@@ -1999,7 +2029,9 @@ int dpll_nl_device_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 			ret = -EMSGSIZE;
 			break;
 		}
+		mutex_lock(&dpll->domain->lock);
 		ret = dpll_device_get_one(dpll, skb, cb->extack);
+		mutex_unlock(&dpll->domain->lock);
 		if (ret) {
 			genlmsg_cancel(skb, hdr);
 			break;

@@ -2018,6 +2050,7 @@ int dpll_nl_device_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 int dpll_pre_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 		  struct genl_info *info)
 {
+	struct dpll_device *dpll;
 	u32 id;
 
 	if (GENL_REQ_ATTR_CHECK(info, DPLL_A_ID))

@@ -2025,11 +2058,13 @@ int dpll_pre_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 
 	mutex_lock(&dpll_lock);
 	id = nla_get_u32(info->attrs[DPLL_A_ID]);
-	info->user_ptr[0] = dpll_device_get_by_id(id);
-	if (!info->user_ptr[0]) {
+	dpll = dpll_device_get_by_id(id);
+	if (!dpll) {
 		NL_SET_ERR_MSG(info->extack, "device not found");
 		goto unlock;
 	}
+	info->user_ptr[0] = dpll;
+	mutex_lock(&dpll->domain->lock);
 	return 0;
 unlock:
 	mutex_unlock(&dpll_lock);

@@ -2039,6 +2074,9 @@ int dpll_pre_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 void dpll_post_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 		    struct genl_info *info)
 {
+	struct dpll_device *dpll = info->user_ptr[0];
+
+	mutex_unlock(&dpll->domain->lock);
 	mutex_unlock(&dpll_lock);
 }
 

@@ -2061,6 +2099,7 @@ dpll_unlock_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 int dpll_pin_pre_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 		      struct genl_info *info)
 {
+	struct dpll_pin *pin;
 	int ret;
 
 	mutex_lock(&dpll_lock);

@@ -2068,14 +2107,14 @@ int dpll_pin_pre_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 		ret = -EINVAL;
 		goto unlock_dev;
 	}
-	info->user_ptr[0] = xa_load(&dpll_pin_xa,
-				    nla_get_u32(info->attrs[DPLL_A_PIN_ID]));
-	if (!info->user_ptr[0] ||
-	    !dpll_pin_available(info->user_ptr[0])) {
+	pin = xa_load(&dpll_pin_xa, nla_get_u32(info->attrs[DPLL_A_PIN_ID]));
+	if (!pin || !dpll_pin_available(pin)) {
 		NL_SET_ERR_MSG(info->extack, "pin not found");
 		ret = -ENODEV;
 		goto unlock_dev;
 	}
+	info->user_ptr[0] = pin;
+	mutex_lock(&pin->domain->lock);
 
 	return 0;
 

@@ -2087,5 +2126,8 @@ int dpll_pin_pre_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 void dpll_pin_post_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 			struct genl_info *info)
 {
+	struct dpll_pin *pin = info->user_ptr[0];
+
+	mutex_unlock(&pin->domain->lock);
 	mutex_unlock(&dpll_lock);
 }