FROMLIST: firmware: arm_scmi: make notify_priv really private

Notification private data is currently accessible via handle->notify_priv;
this data was indeed meant to be private to the notification core support
and not to be accessible by SCMI drivers: make it private hiding it inside
instance descriptor struct scmi_info and accessible only via dedicated
helpers.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>

Bug: 171409184
Link: https://lore.kernel.org/linux-arm-kernel/20210202221555.41167-1-cristian.marussi@arm.com/
Change-Id: Ic0a1c0610f9726f3ebde388e685ee20343533d33
Signed-off-by: Rishabh Bhatnagar <quic_rishabhb@quicinc.com>

drivers/firmware/arm_scmi/common.h

@@ -341,4 +341,8 @@ void shmem_clear_channel(struct scmi_shared_mem __iomem *shmem);
 bool shmem_poll_done(struct scmi_shared_mem __iomem *shmem,
 		     struct scmi_xfer *xfer);
 
+void scmi_set_notification_instance_data(const struct scmi_handle *handle,
+					 void *priv);
+void *scmi_get_notification_instance_data(const struct scmi_handle *handle);
+
 #endif /* _SCMI_COMMON_H */

drivers/firmware/arm_scmi/driver.c

@@ -113,6 +113,7 @@ struct scmi_protocol_instance {
  * @protocols_mtx: A mutex to protect protocols instances initialization.
  * @protocols_imp: List of protocols implemented, currently maximum of
  *	MAX_PROTOCOLS_IMP elements allocated by the base protocol
+ * @notify_priv: Pointer to private data structure specific to notifications.
  * @node: List head
  * @users: Number of users of this instance
  */
@@ -129,6 +130,7 @@ struct scmi_info {
 	/* Ensure mutual exclusive access to protocols instance array */
 	struct mutex protocols_mtx;
 	u8 *protocols_imp;
+	void *notify_priv;
 	struct list_head node;
 	int users;
 };
@@ -170,6 +172,25 @@ static inline void scmi_dump_header_dbg(struct device *dev,
 		hdr->id, hdr->seq, hdr->protocol_id);
 }
 
+void scmi_set_notification_instance_data(const struct scmi_handle *handle,
+					 void *priv)
+{
+	struct scmi_info *info = handle_to_scmi_info(handle);
+
+	info->notify_priv = priv;
+	/* Ensure updated protocol private date are visible */
+	smp_wmb();
+}
+
+void *scmi_get_notification_instance_data(const struct scmi_handle *handle)
+{
+	struct scmi_info *info = handle_to_scmi_info(handle);
+
+	/* Ensure protocols_private_data has been updated */
+	smp_rmb();
+	return info->notify_priv;
+}
+
 /**
  * scmi_xfer_get() - Allocate one message
  *

drivers/firmware/arm_scmi/notify.c

@@ -582,11 +582,9 @@ int scmi_notify(const struct scmi_handle *handle, u8 proto_id, u8 evt_id,
 	struct scmi_event_header eh;
 	struct scmi_notify_instance *ni;
 
-	/* Ensure notify_priv is updated */
-	smp_rmb();
-	if (!handle->notify_priv)
+	ni = scmi_get_notification_instance_data(handle);
+	if (!ni)
 		return 0;
-	ni = handle->notify_priv;
 
 	r_evt = SCMI_GET_REVT(ni, proto_id, evt_id);
 	if (!r_evt)
@@ -762,11 +760,9 @@ int scmi_register_protocol_events(const struct scmi_handle *handle, u8 proto_id,
 	    (!ee->num_sources && !ee->ops->get_num_sources))
 		return -EINVAL;
 
-	/* Ensure notify_priv is updated */
-	smp_rmb();
-	if (!handle->notify_priv)
+	ni = scmi_get_notification_instance_data(handle);
+	if (!ni)
 		return -ENOMEM;
-	ni = handle->notify_priv;
 
 	/* num_sources cannot be <= 0 */
 	if (ee->num_sources) {
@@ -851,12 +847,10 @@ void scmi_deregister_protocol_events(const struct scmi_handle *handle,
 	struct scmi_notify_instance *ni;
 	struct scmi_registered_events_desc *pd;
 
-	/* Ensure notify_priv is updated */
-	smp_rmb();
-	if (!handle->notify_priv)
+	ni = scmi_get_notification_instance_data(handle);
+	if (!ni)
 		return;
 
-	ni = handle->notify_priv;
 	pd = ni->registered_protocols[proto_id];
 	if (!pd)
 		return;
@@ -1359,11 +1353,9 @@ static int scmi_register_notifier(const struct scmi_handle *handle,
 	struct scmi_event_handler *hndl;
 	struct scmi_notify_instance *ni;
 
-	/* Ensure notify_priv is updated */
-	smp_rmb();
-	if (!handle->notify_priv)
+	ni = scmi_get_notification_instance_data(handle);
+	if (!ni)
 		return -ENODEV;
-	ni = handle->notify_priv;
 
 	evt_key = MAKE_HASH_KEY(proto_id, evt_id,
 				src_id ? *src_id : SRC_ID_MASK);
@@ -1407,11 +1399,9 @@ static int scmi_unregister_notifier(const struct scmi_handle *handle,
 	struct scmi_event_handler *hndl;
 	struct scmi_notify_instance *ni;
 
-	/* Ensure notify_priv is updated */
-	smp_rmb();
-	if (!handle->notify_priv)
+	ni = scmi_get_notification_instance_data(handle);
+	if (!ni)
 		return -ENODEV;
-	ni = handle->notify_priv;
 
 	evt_key = MAKE_HASH_KEY(proto_id, evt_id,
 				src_id ? *src_id : SRC_ID_MASK);
@@ -1684,8 +1674,8 @@ int scmi_notification_init(struct scmi_handle *handle)
 
 	INIT_WORK(&ni->init_work, scmi_protocols_late_init);
 
+	scmi_set_notification_instance_data(handle, ni);
 	handle->notify_ops = &notify_ops;
-	handle->notify_priv = ni;
 	/* Ensure handle is up to date */
 	smp_wmb();
 
@@ -1697,7 +1687,7 @@ int scmi_notification_init(struct scmi_handle *handle)
 
 err:
 	dev_warn(handle->dev, "Initialization Failed.\n");
-	devres_release_group(handle->dev, NULL);
+	devres_release_group(handle->dev, gid);
 	return -ENOMEM;
 }
 
@@ -1709,15 +1699,10 @@ void scmi_notification_exit(struct scmi_handle *handle)
 {
 	struct scmi_notify_instance *ni;
 
-	/* Ensure notify_priv is updated */
-	smp_rmb();
-	if (!handle->notify_priv)
+	ni = scmi_get_notification_instance_data(handle);
+	if (!ni)
 		return;
-	ni = handle->notify_priv;
-
-	handle->notify_priv = NULL;
-	/* Ensure handle is up to date */
-	smp_wmb();
+	scmi_set_notification_instance_data(handle, NULL);
 
 	/* Destroy while letting pending work complete */
 	destroy_workqueue(ni->notify_wq);

include/linux/scmi_protocol.h

@@ -612,8 +612,6 @@ struct scmi_notify_ops {
  * @devm_put_protocol: devres managed method to release a protocol acquired
  *		       with devm_acquire/get_protocol
  * @notify_ops: pointer to set of notifications related operations
- * @notify_priv: pointer to private data structure specific to notifications
- *	(for internal use only)
  */
 struct scmi_handle {
 	struct device *dev;
@@ -627,7 +625,6 @@ struct scmi_handle {
 	void (*devm_put_protocol)(struct scmi_device *sdev, u8 proto);
 
 	const struct scmi_notify_ops *notify_ops;
-	void *notify_priv;
 };
 
 enum scmi_std_protocol {