1 files changed, 102 insertions, 78 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 832d4eae501e..2db62d98e395 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -136,6 +136,50 @@ static int device_is_dependent(struct device *dev, void *target)
 	return ret;
 }
 
+static void device_link_init_status(struct device_link *link,
+				    struct device *consumer,
+				    struct device *supplier)
+{
+	switch (supplier->links.status) {
+	case DL_DEV_PROBING:
+		switch (consumer->links.status) {
+		case DL_DEV_PROBING:
+			/*
+			 * A consumer driver can create a link to a supplier
+			 * that has not completed its probing yet as long as it
+			 * knows that the supplier is already functional (for
+			 * example, it has just acquired some resources from the
+			 * supplier).
+			 */
+			link->status = DL_STATE_CONSUMER_PROBE;
+			break;
+		default:
+			link->status = DL_STATE_DORMANT;
+			break;
+		}
+		break;
+	case DL_DEV_DRIVER_BOUND:
+		switch (consumer->links.status) {
+		case DL_DEV_PROBING:
+			link->status = DL_STATE_CONSUMER_PROBE;
+			break;
+		case DL_DEV_DRIVER_BOUND:
+			link->status = DL_STATE_ACTIVE;
+			break;
+		default:
+			link->status = DL_STATE_AVAILABLE;
+			break;
+		}
+		break;
+	case DL_DEV_UNBINDING:
+		link->status = DL_STATE_SUPPLIER_UNBIND;
+		break;
+	default:
+		link->status = DL_STATE_DORMANT;
+		break;
+	}
+}
+
 static int device_reorder_to_tail(struct device *dev, void *not_used)
 {
 	struct device_link *link;
@@ -177,6 +221,13 @@ void device_pm_move_to_tail(struct device *dev)
 	device_links_read_unlock(idx);
 }
 
+#define DL_MANAGED_LINK_FLAGS (DL_FLAG_AUTOREMOVE_CONSUMER | \
+			       DL_FLAG_AUTOREMOVE_SUPPLIER | \
+			       DL_FLAG_AUTOPROBE_CONSUMER)
+
+#define DL_ADD_VALID_FLAGS (DL_MANAGED_LINK_FLAGS | DL_FLAG_STATELESS | \
+			    DL_FLAG_PM_RUNTIME | DL_FLAG_RPM_ACTIVE)
+
 /**
  * device_link_add - Create a link between two devices.
  * @consumer: Consumer end of the link.
@@ -191,9 +242,9 @@ void device_pm_move_to_tail(struct device *dev)
  * of the link.  If DL_FLAG_PM_RUNTIME is not set, DL_FLAG_RPM_ACTIVE will be
  * ignored.
  *
- * If DL_FLAG_STATELESS is set in @flags, the link is not going to be managed by
- * the driver core and, in particular, the caller of this function is expected
- * to drop the reference to the link acquired by it directly.
+ * If DL_FLAG_STATELESS is set in @flags, the caller of this function is
+ * expected to release the link returned by it directly with the help of either
+ * device_link_del() or device_link_remove().
  *
  * If that flag is not set, however, the caller of this function is handing the
  * management of the link over to the driver core entirely and its return value
@@ -213,9 +264,16 @@ void device_pm_move_to_tail(struct device *dev)
  * be used to request the driver core to automaticall probe for a consmer
  * driver after successfully binding a driver to the supplier device.
  *
- * The combination of DL_FLAG_STATELESS and either DL_FLAG_AUTOREMOVE_CONSUMER
- * or DL_FLAG_AUTOREMOVE_SUPPLIER set in @flags at the same time is invalid and
- * will cause NULL to be returned upfront.
+ * The combination of DL_FLAG_STATELESS and one of DL_FLAG_AUTOREMOVE_CONSUMER,
+ * DL_FLAG_AUTOREMOVE_SUPPLIER, or DL_FLAG_AUTOPROBE_CONSUMER set in @flags at
+ * the same time is invalid and will cause NULL to be returned upfront.
+ * However, if a device link between the given @consumer and @supplier pair
+ * exists already when this function is called for them, the existing link will
+ * be returned regardless of its current type and status (the link's flags may
+ * be modified then).  The caller of this function is then expected to treat
+ * the link as though it has just been created, so (in particular) if
+ * DL_FLAG_STATELESS was passed in @flags, the link needs to be released
+ * explicitly when not needed any more (as stated above).
  *
  * A side effect of the link creation is re-ordering of dpm_list and the
  * devices_kset list by moving the consumer device and all devices depending
@@ -231,11 +289,8 @@ struct device_link *device_link_add(struct device *consumer,
 {
 	struct device_link *link;
 
-	if (!consumer || !supplier ||
-	    (flags & DL_FLAG_STATELESS &&
-	     flags & (DL_FLAG_AUTOREMOVE_CONSUMER |
-		      DL_FLAG_AUTOREMOVE_SUPPLIER |
-		      DL_FLAG_AUTOPROBE_CONSUMER)) ||
+	if (!consumer || !supplier || flags & ~DL_ADD_VALID_FLAGS ||
+	    (flags & DL_FLAG_STATELESS && flags & DL_MANAGED_LINK_FLAGS) ||
 	    (flags & DL_FLAG_AUTOPROBE_CONSUMER &&
 	     flags & (DL_FLAG_AUTOREMOVE_CONSUMER |
 		      DL_FLAG_AUTOREMOVE_SUPPLIER)))
@@ -248,6 +303,9 @@ struct device_link *device_link_add(struct device *consumer,
 		}
 	}
 
+	if (!(flags & DL_FLAG_STATELESS))
+		flags |= DL_FLAG_MANAGED;
+
 	device_links_write_lock();
 	device_pm_lock();
 
@@ -274,15 +332,6 @@ struct device_link *device_link_add(struct device *consumer,
 		if (link->consumer != consumer)
 			continue;
 
-		/*
-		 * Don't return a stateless link if the caller wants a stateful
-		 * one and vice versa.
-		 */
-		if (WARN_ON((flags & DL_FLAG_STATELESS) != (link->flags & DL_FLAG_STATELESS))) {
-			link = NULL;
-			goto out;
-		}
-
 		if (flags & DL_FLAG_PM_RUNTIME) {
 			if (!(link->flags & DL_FLAG_PM_RUNTIME)) {
 				pm_runtime_new_link(consumer);
@@ -293,6 +342,7 @@ struct device_link *device_link_add(struct device *consumer,
 		}
 
 		if (flags & DL_FLAG_STATELESS) {
+			link->flags |= DL_FLAG_STATELESS;
 			kref_get(&link->kref);
 			goto out;
 		}
@@ -311,6 +361,11 @@ struct device_link *device_link_add(struct device *consumer,
 			link->flags &= ~(DL_FLAG_AUTOREMOVE_CONSUMER |
 					 DL_FLAG_AUTOREMOVE_SUPPLIER);
 		}
+		if (!(link->flags & DL_FLAG_MANAGED)) {
+			kref_get(&link->kref);
+			link->flags |= DL_FLAG_MANAGED;
+			device_link_init_status(link, consumer, supplier);
+		}
 		goto out;
 	}
 
@@ -337,48 +392,10 @@ struct device_link *device_link_add(struct device *consumer,
 	kref_init(&link->kref);
 
 	/* Determine the initial link state. */
-	if (flags & DL_FLAG_STATELESS) {
+	if (flags & DL_FLAG_STATELESS)
 		link->status = DL_STATE_NONE;
-	} else {
-		switch (supplier->links.status) {
-		case DL_DEV_PROBING:
-			switch (consumer->links.status) {
-			case DL_DEV_PROBING:
-				/*
-				 * A consumer driver can create a link to a
-				 * supplier that has not completed its probing
-				 * yet as long as it knows that the supplier is
-				 * already functional (for example, it has just
-				 * acquired some resources from the supplier).
-				 */
-				link->status = DL_STATE_CONSUMER_PROBE;
-				break;
-			default:
-				link->status = DL_STATE_DORMANT;
-				break;
-			}
-			break;
-		case DL_DEV_DRIVER_BOUND:
-			switch (consumer->links.status) {
-			case DL_DEV_PROBING:
-				link->status = DL_STATE_CONSUMER_PROBE;
-				break;
-			case DL_DEV_DRIVER_BOUND:
-				link->status = DL_STATE_ACTIVE;
-				break;
-			default:
-				link->status = DL_STATE_AVAILABLE;
-				break;
-			}
-			break;
-		case DL_DEV_UNBINDING:
-			link->status = DL_STATE_SUPPLIER_UNBIND;
-			break;
-		default:
-			link->status = DL_STATE_DORMANT;
-			break;
-		}
-	}
+	else
+		device_link_init_status(link, consumer, supplier);
 
 	/*
 	 * Some callers expect the link creation during consumer driver probe to
@@ -540,7 +557,7 @@ static void device_links_missing_supplier(struct device *dev)
  * mark the link as "consumer probe in progress" to make the supplier removal
  * wait for us to complete (or bad things may happen).
  *
- * Links with the DL_FLAG_STATELESS flag set are ignored.
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
  */
 int device_links_check_suppliers(struct device *dev)
 {
@@ -550,7 +567,7 @@ int device_links_check_suppliers(struct device *dev)
 	device_links_write_lock();
 
 	list_for_each_entry(link, &dev->links.suppliers, c_node) {
-		if (link->flags & DL_FLAG_STATELESS)
+		if (!(link->flags & DL_FLAG_MANAGED))
 			continue;
 
 		if (link->status != DL_STATE_AVAILABLE) {
@@ -575,7 +592,7 @@ int device_links_check_suppliers(struct device *dev)
  *
  * Also change the status of @dev's links to suppliers to "active".
  *
- * Links with the DL_FLAG_STATELESS flag set are ignored.
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
  */
 void device_links_driver_bound(struct device *dev)
 {
@@ -584,7 +601,7 @@ void device_links_driver_bound(struct device *dev)
 	device_links_write_lock();
 
 	list_for_each_entry(link, &dev->links.consumers, s_node) {
-		if (link->flags & DL_FLAG_STATELESS)
+		if (!(link->flags & DL_FLAG_MANAGED))
 			continue;
 
 		/*
@@ -605,7 +622,7 @@ void device_links_driver_bound(struct device *dev)
 	}
 
 	list_for_each_entry(link, &dev->links.suppliers, c_node) {
-		if (link->flags & DL_FLAG_STATELESS)
+		if (!(link->flags & DL_FLAG_MANAGED))
 			continue;
 
 		WARN_ON(link->status != DL_STATE_CONSUMER_PROBE);
@@ -617,6 +634,13 @@ void device_links_driver_bound(struct device *dev)
 	device_links_write_unlock();
 }
 
+static void device_link_drop_managed(struct device_link *link)
+{
+	link->flags &= ~DL_FLAG_MANAGED;
+	WRITE_ONCE(link->status, DL_STATE_NONE);
+	kref_put(&link->kref, __device_link_del);
+}
+
 /**
  * __device_links_no_driver - Update links of a device without a driver.
  * @dev: Device without a drvier.
@@ -627,18 +651,18 @@ void device_links_driver_bound(struct device *dev)
  * unless they already are in the "supplier unbind in progress" state in which
  * case they need not be updated.
  *
- * Links with the DL_FLAG_STATELESS flag set are ignored.
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
  */
 static void __device_links_no_driver(struct device *dev)
 {
 	struct device_link *link, *ln;
 
 	list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
-		if (link->flags & DL_FLAG_STATELESS)
+		if (!(link->flags & DL_FLAG_MANAGED))
 			continue;
 
 		if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER)
-			__device_link_del(&link->kref);
+			device_link_drop_managed(link);
 		else if (link->status == DL_STATE_CONSUMER_PROBE ||
 			 link->status == DL_STATE_ACTIVE)
 			WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
@@ -655,7 +679,7 @@ static void __device_links_no_driver(struct device *dev)
  * %__device_links_no_driver() to update links to suppliers for it as
  * appropriate.
  *
- * Links with the DL_FLAG_STATELESS flag set are ignored.
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
  */
 void device_links_no_driver(struct device *dev)
 {
@@ -664,7 +688,7 @@ void device_links_no_driver(struct device *dev)
 	device_links_write_lock();
 
 	list_for_each_entry(link, &dev->links.consumers, s_node) {
-		if (link->flags & DL_FLAG_STATELESS)
+		if (!(link->flags & DL_FLAG_MANAGED))
 			continue;
 
 		/*
@@ -692,7 +716,7 @@ void device_links_no_driver(struct device *dev)
  * invoke %__device_links_no_driver() to update links to suppliers for it as
  * appropriate.
  *
- * Links with the DL_FLAG_STATELESS flag set are ignored.
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
  */
 void device_links_driver_cleanup(struct device *dev)
 {
@@ -701,7 +725,7 @@ void device_links_driver_cleanup(struct device *dev)
 	device_links_write_lock();
 
 	list_for_each_entry_safe(link, ln, &dev->links.consumers, s_node) {
-		if (link->flags & DL_FLAG_STATELESS)
+		if (!(link->flags & DL_FLAG_MANAGED))
 			continue;
 
 		WARN_ON(link->flags & DL_FLAG_AUTOREMOVE_CONSUMER);
@@ -714,7 +738,7 @@ void device_links_driver_cleanup(struct device *dev)
 		 */
 		if (link->status == DL_STATE_SUPPLIER_UNBIND &&
 		    link->flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
-			__device_link_del(&link->kref);
+			device_link_drop_managed(link);
 
 		WRITE_ONCE(link->status, DL_STATE_DORMANT);
 	}
@@ -736,7 +760,7 @@ void device_links_driver_cleanup(struct device *dev)
  *
  * Return 'false' if there are no probing or active consumers.
  *
- * Links with the DL_FLAG_STATELESS flag set are ignored.
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
  */
 bool device_links_busy(struct device *dev)
 {
@@ -746,7 +770,7 @@ bool device_links_busy(struct device *dev)
 	device_links_write_lock();
 
 	list_for_each_entry(link, &dev->links.consumers, s_node) {
-		if (link->flags & DL_FLAG_STATELESS)
+		if (!(link->flags & DL_FLAG_MANAGED))
 			continue;
 
 		if (link->status == DL_STATE_CONSUMER_PROBE
@@ -776,7 +800,7 @@ bool device_links_busy(struct device *dev)
  * driver to unbind and start over (the consumer will not re-probe as we have
  * changed the state of the link already).
  *
- * Links with the DL_FLAG_STATELESS flag set are ignored.
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
  */
 void device_links_unbind_consumers(struct device *dev)
 {
@@ -788,7 +812,7 @@ void device_links_unbind_consumers(struct device *dev)
 	list_for_each_entry(link, &dev->links.consumers, s_node) {
 		enum device_link_state status;
 
-		if (link->flags & DL_FLAG_STATELESS)
+		if (!(link->flags & DL_FLAG_MANAGED))
 			continue;
 
 		status = link->status;